Rapidly acting dry sealant and methods for use and manufacture

ABSTRACT

Compositions, methods, and kits are provided for sealing applications. Compositions are prepared by combining a first cross-linkable component with a second cross-linkable component to form a porous matrix having interstices, and combining the porous matrix with a hydrogel-forming component to fill at least some of the interstices. The compositions exhibit minimal swelling properties.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/832,380 filed Aug. 1, 2007, which claims the benefit of priority fromU.S. Patent Application No. 60/821,190 filed Aug. 2, 2006. Thisapplication is also related to U.S. Pat. Nos. 5,874,500, 6,063,061,6,066,325, 6,166,130, and 6,458,889. The contents of each of thesefilings are hereby incorporated by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

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REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAMLISTING APPENDIX SUBMITTED ON A COMPACT DISK

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BACKGROUND OF THE INVENTION

U.S. Pat. No. 5,162,430, issued Nov. 10, 1992, to Rhee et al. discussescollagen-synthetic polymer conjugates prepared by covalently bindingcollagen to synthetic hydrophilic polymers such as various derivativesof polyethylene glycol. U.S. Pat. No. 5,324,775, issued Jun. 28, 1994,to Rhee et al. discusses various insert, naturally occurring,biocompatible polymers (such as polysaccharides) covalently bound tosynthetic, non-immunogenic, hydrophilic polyethylene glycol polymers.U.S. Pat. No. 5,328,955, issued Jul. 12, 1994, to Rhee et al. discussesvarious activated forms of polyethylene glycol and various linkageswhich can be used to produce collagen-synthetic polymer conjugateshaving a range of physical and chemical properties.

Ser. No. 08/403,358, filed Mar. 14, 1995, discusses a crosslinkedbiomaterial composition that is prepared using a hydrophobiccrosslinking agent, or a mixture of hydrophilic and hydrophobiccrosslinking agents. Hydrophobic crosslinking agents can include anyhydrophobic polymer that contains, or can be chemically derivatized tocontain, two or more succinimidyl groups.

U.S. Pat. No. 5,580,923, issued Dec. 3, 1996, to Yeung et al. discussesa composition useful in the prevention of surgical adhesions comprisinga substrate material and an anti-adhesion binding agent, where thesubstrate material preferably comprises collagen and the binding agentpreferably comprises at least one tissue-reactive functional group andat least one substrate-reactive functional group.

U.S. Pat. No. 5,614,587, issued Mar. 25, 1997, to Rhee et al. discussesbioadhesive compositions comprising collagen crosslinked using amultifunctionally activated synthetic hydrophilic polymer, as well asmethods of using such compositions to effect adhesion between a firstsurface and a second surface, wherein at least one of the first andsecond surfaces can be a native tissue surface.

Japanese patent publication No. 07090241 discusses a composition usedfor temporary adhesion of a lens material to a support, to mount thematerial on a machining device, comprising a mixture of polyethyleneglycol, having an average molecular weight in the range of 1000-5000,and poly-N-vinylpyrrolidone, having an average molecular weight in therange of 30,000-200,000.

West and Hubbell, Biomaterials (1995) 16:1153-1156, discuss theprevention of post-operative adhesions using a photopolymerizedpolyethylene glycol-co-lactic acid diacrylate hydrogel and a physicallycrosslinked polyethylene glycol-co-polypropylene glycol hydrogel,Poloxamer 407®.

U.S. Pat. Nos. 5,672,336 and 5,196,185 describe a wound dressingcomprising a micro-particulate fibrillar collagen having a particle sizeof 0.5-2.0 μm. This composition generally comprises an aqueous phase andmay not form a hydrogel as described in the present invention. U.S. Pat.No. 5,698,213 describes a cross-linked aliphatic poly-ester hydrogeluseful as an absorbable surgical device and drug delivery vehicle. U.S.Pat. No. 5,674,275 describes an acrylate or methacrylate based hydrogeladhesive. U.S. Pat. No. 5,306,501 describes a polyoxyalkylene basedthermoreversible hydrogel useful as a drug delivery vehicle.

U.S. Pat. Nos. 4,925,677 and 5,041,292 describe a hydrogel comprising aprotein component cross-linked with a polysaccharide ormucopolysaccharide and useful as a drug delivery vehicle.

Biodegradable injectable drug delivery polymers are described in U.S.Pat. No. 5,384,333 and by Jeong et al. (1997) “Nature,” 388:860-862.Biodegradable hydrogels for controlled released drug delivery aredescribed in U.S. Pat. No. 4,925,677. Resorbable collagen-based drugdelivery systems are described in U.S. Pat. Nos. 4,347,234 and4,291,013. Aminopolysaccharide-based biocompatible films for drugdelivery are described in U.S. Pat. Nos. 5,300,494 and 4,946,870. Watersoluble carriers for the delivery of taxol are described in U.S. Pat.No. 5,648,506.

Polymers have been used as carriers of therapeutic agents to effect alocalized and sustained release (Langer, et al., Rev. Macro. Chem.Phys., C23 (1), 61, 1983; Controlled Drug Delivery, Vol. I and II,Bruck, S. D., (ed.), CRC Press, Boca Raton, Fla., 1983; Leong et al.,Adv. Drug Delivery Review, 1:199, 1987). These therapeutic agentdelivery systems simulate infusion and offer the potential of enhancedtherapeutic efficacy and reduced systemic toxicity.

Other classes of synthetic polymers which have been proposed forcontrolled release drug delivery include polyesters (Pitt, et al., inControlled Release of Bioactive Materials, R. Baker, Ed., AcademicPress, New York, 1980); polyamides (Sidman, et al., Journal of MembraneScience, 7:227, 1979); polyurethanes (Maser, et al., Journal of PolymerScience, Polymer Symposium, 66:259, 1979); polyorthoesters (Heller, etal., Polymer Engineering Scient, 21:727, 1981); and polyanhydrides(Leong, et al., Biomaterials, 7:364, 1986).

Collagen-containing compositions which have been mechanically disruptedto alter their physical properties are described in U.S. Pat. Nos.5,428,024; 5,352,715; and 5,204,382. These patents generally relate tofibrillar and insoluble collagens. An injectable collagen composition isdescribed in U.S. Pat. No. 4,803,075. An injectable bone/cartilagecomposition is described in U.S. Pat. No. 5,516,532. A collagen-baseddelivery matrix comprising dry particles in the size range from 5 μm to850 μm which may be suspended in water and which has a particularsurface charge density is described in WO 96/39159. A collagenpreparation having a particle size from 1 μm to 50 μm useful as anaerosol spray to form a wound dressing is described in U.S. Pat. No.5,196,185. Other patents describing collagen compositions include U.S.Pat. Nos. 5,672,336 and 5,356,614. A polymeric, non-erodible hydrogelthat may be cross-linked and injected via a syringe is described in WO96/06883.

The following pending applications, assigned to the assignee of thepresent application, contain related subject matter: U.S. Ser. No.08/903,674, filed on Jul. 31, 1997; U.S. Ser. No. 60/050,437, filed onJun. 18, 1997; U.S. Ser. No. 08/704,852, filed on Aug. 27, 1996; U.S.Ser. No. 08/673,710, filed Jun. 19, 1996; U.S. Ser. No. 60/011,898,filed Feb. 20, 1996; U.S. Ser. No. 60/006,321, filed on Nov. 7, 1996;U.S. Ser. No. 60/006,322, filed on Nov. 7, 1996; U.S. Ser. No.60/006,324, filed on Nov. 7, 1996; and U.S. Ser. No. 08/481,712, filedon Jun. 7, 1995. The full disclosures of each of these applications isincorporated herein by reference. Each publication cited above andherein is incorporated herein by reference in its entirety. There are avariety of materials suitable for use as bioadhesives, for tissueaugmentation, for the prevention of surgical adhesions, for coatingsurfaces of synthetic implants, as drug delivery matrices, forophthalmic applications, and the like. Yet in many cases the settingtime for these materials can be less than optimal, whereas for surgicaland other medical applications, a rapidly acting material is oftenpreferred. In other cases, currently available materials may exhibitswelling properties that are undesirable for certain surgicalapplications. Thus, what is needed is a rapidly acting material, for useas, for example, a tissue sealant for hemostatic and/or wound sealingapplications. It would also be desirable to provide materials thatexhibit minimal swelling properties.

BRIEF SUMMARY OF THE INVENTION

The present invention provides compositions for the achievement ofhemostasis or other fluid containment in an in vivo context. Thecompositions of the invention comprise first and second cross-linkablecomponents and at least one hydrogel-forming component, in a compositionsuitable for applying to a vertebrate to facilitate fluid containment.Compositions include rapidly acting materials, for use as, for example,a tissue sealant for hemostatic and/or wound sealing applications.Compositions exhibit minimal swelling properties.

In a first aspect, embodiments of the present invention provide acomposition that includes a first cross-linkable component, a secondcross-linkable component that cross-links with the first cross-linkablecomponent under reaction enabling conditions, and a hydrogel-formingcomponent. The first and second cross-linkable component cross-link toform a porous matrix having interstices, and the hydrogel-formingcomponent is capable of being hydrated to form a hydrogel to fill atleast some of the interstices. In some aspects, the pH of thehydrogel-forming component may affect a reaction time for forming asealant matrix barrier. For example, in some embodiments, a compositionthat includes a hydrogel-forming component having a pH of 6.75 providesa slower reaction time than composition that includes a hydrogel-formingcomponent having a pH of 9.5.

The first cross-linkable component can include multiple nucleophilicgroups and the second cross-linkable component can include multipleelectrophilic groups. In some aspects, the first cross-linkablecomponent includes a multi-nucleophilic polyalkylene oxide having mnucleophilic groups, and the second cross-linkable component includes amulti-electrophilic polyalkylene oxide having n electrophilic groups,where m and n are each greater than or equal to two, and wherein m+n isgreater than or equal to five. In some aspects, n is two, and m isgreater than or equal to three. The multi-nucleophilic polyalkyleneoxide can be tetrafunctionally activated. In some aspects, m is two, andn is greater than or equal to three. The multi-electrophilicpolyalkylene oxide can be tetrafunctionally activated. In some cases,both the multi-nucleophilic polyalkylene oxide and themulti-electrophilic polyalkylene oxide are tetrafunctionally activated.The multi-nucleophilic polyalkylene oxide can include two or morenucleophilic groups, for example NH₂, —SH, —H, —PH₂, and/or —CO—NH—NH₂.In some cases, the multi-nucleophilic polyalkylene oxide includes two ormore primary amino groups. In some cases, the multi-nucleophilicpolyalkylene oxide includes two or more thiol groups. Themulti-nucleophilic polyalkylene oxide can be polyethylene glycol or aderivative thereof. In some cases, the polyethylene glycol includes twoor more nucleophilic groups, which may include a primary amino groupand/or a thiol group. The multi-electrophilic polyalkylene oxide caninclude two or more electrophilic groups such as —CO₂N(COCH₂)₂, —CO₂H,—CHO, —CHOCH₂, —N═C═O, —SO₂CH═CH₂, —N(COCH)₂, and/or —S—S—(C₅H₄N). Themulti-electrophilic polyalkylene oxide may include two or moresuccinimidyl groups. The multi-electrophilic polyalkylene oxide mayinclude two or more maleimidyl groups. In some cases, themulti-electrophilic polyalkylene oxide can be a polyethylene glycol or aderivative thereof.

In some aspects, the composition includes a polysaccharide or a protein.The polysaccharide can be a glycosaminoglycan, such as hyaluronic acid,chitin, chondroitin sulfate A, chondroitin sulfate B, chondroitinsulfate C, keratin sulfate, keratosulfate, heparin, or a derivativethereof. The protein can be collagen or a derivative thereof. Themulti-nucleophilic polyalkylene oxide or the multi-electrophilicpolyalkylene oxide, or both the multi-nucleophilic polyalkylene oxideand the multi-electrophilic polyalkylene oxide, may include a linkinggroup. In some cases, the multi-nucleophilic polyalkylene oxide can begiven by the formula: polymer-Q¹-X_(m). The multi-electrophilicpolyalkylene oxide can be given by the formula: polymer-Q²-Y_(n). X canbe a electrophilic group and Y can be a nucleophilic group, m and n caneach be 2 to 4, m+n can be ≦5, and each of Q¹ and Q² can be linkinggroups such as —O—(CH₂)_(n′)—, —S—, —(CH₂)_(n′)—, —NH—(CH₂)_(n′)—,—O₂C—NH—(CH₂)_(n′)—, —O₂C—(CH₂)_(n′)—, —O₂C—CR¹H, and/or —O—R²—CO—NH. Insome cases, n′ can be 1 to 10, R¹ can be —H, —CH₃, or —C₂H₅, R² can be—CH₂— or —CO—NH—CH₂CH₂—, and Q¹ and Q² can be the same or different orcan be absent. In some aspects, Y can be —CO₂N(COCH₂)₂ or —CO₂N(COCH₂)₂.In some cases, the multi-nucleophilic polykylene oxide or themulti-electrophilic polyalkylene oxide, or both the multi-nucleophilicpolyalkylene oxide and the multi-electrophilic polyalkylene oxide,further include a biodegradable group. The biodegradable group can be alactide, glycolide, ε-caprolactone, poly(α-hydroxy acid), poly(aminoacid), or a poly(anhydride). In some aspects, the hydrogel formingcomponent is capable of being hydrated to form a fragmentedbiocompatible hydrogel that includes gelatin and absorbs water whendelivered to a moist tissue target site. The hydrogel can includesubunits having sizes ranging from about 0.01 mm to about 5 mm whenfully hydrated and an equilibrium swell ranging from about 400% to about5000%. In some cases, the hydrogel has an in vivo degradation time ofless than one year. In some cases, the hydrogel is at least partiallyhydrated with an aqueous medium and includes an active agent, which mayinclude a clotting agent, such as thrombin.

In another aspect, embodiments of the present invention provide a methodfor delivering an active agent to a patient. The method can includeadministering to a target site on the patient an amount of a compositionas described herein. In some aspects, embodiments include a method fordelivering a sealing agent to a patient. The method can includeadministering to a bleeding target site an amount of a composition asdescribed herein in an amount sufficient to inhibit bleeding. In someaspects, embodiments include a method for delivering thrombin to apatient. The method can include administering to a bleeding target sitean amount of a composition as described herein in an amount sufficientto inhibit bleeding.

In still another aspect, embodiments of the present invention encompassa composition that includes a multi-nucleophilic polyalkylene oxide, amulti-electrophilic polyalkylene oxide, and a hydrogel formingcomponent. The multi-nucleophilic polyalkylene oxide further can includeat least one primary amino group and at least one thiol group. Underreaction-enabling conditions the multi-nucleophilic polyalkylene oxideand multi-electrophilic polyalkylene oxide are capable of substantiallyimmediate cross linking. Embodiments encompass compositions where themulti-nucleophilic polyalkylene oxide includes two or more thiol groupsand the multi-electrophilic polyalkylene oxide includes two or moreelectrophilic groups such as a succinimidyl group and/or a maleimidylgroup. Embodiments also encompass compositions where themulti-nucleophilic polyalkylene oxide includes two or more nucleophilicgroups such as a primary amino group and/or a thiol groups. Themulti-electrophilic polyalkylene oxide can include two or moresuccinimidyl groups. In some cases, embodiments encompass compositionsthat include a first polyethylene glycol having two or more thiolgroups, a second polyethylene glycol having two or more succinimidylgroups or maleimidyl groups, and a hydrogel forming component. The sumof the thiol groups and the succinimidyl or maleimidyl groups may be atleast five, and under reaction-enabling conditions the firstpolyethylene glycol and second polyethylene glycol may be capable ofsubstantially immediate cross linking. In some cases, the firstpolyethylene glycol includes four thiol groups and the secondpolyethylene glycol includes four succinimidyl groups. In some cases,the composition includes a protein or a polysaccharide. Thepolysaccharide can be a glycosaminoglycan, such as hyaluronic acid,chitin, chondroitin sulfate A, chondroitin sulfate B, chondroitinsulfate C, keratin sulfate, keratosulfate, heparin, or a derivativethereof. The protein can be collagen or a derivative thereof.

In another aspect, embodiments of the present invention include a methodfor sealing a tissue tract. The method can include at least partlyfilling a tissue tract with a composition that includes a firstcross-linkable component, a second cross-linkable component thatcross-links with the first cross-linkable component under reactionenabling conditions, and a hydrogel-forming component. The first andsecond cross-linkable components can cross-link to form a porous matrixhaving interstices, and the hydrogel-forming component can be capable ofbeing hydrated to form a hydrogel to fill at least some of theinterstices. In some cases, the hydrogel includes subunits that havesizes ranging from about 0.05 mm to about 5 mm when fully hydrated, thathave an equilibrium swell ranging from about 400% to about 1300%, andthat degrade in the tissue tract after from about 1 to about 120 days.In some cases, the first cross-linkable component includes multiplenucleophilic groups and the second polymer comprises multipleelectrophilic groups.

In still another aspect, embodiments of the present invention include amethod for inhibiting bleeding at a target site in a patient's body. Themethod can include delivering a composition to the target site in anamount sufficient to inhibit bleeding, where the composition includes afirst cross-linkable component, a second cross-linkable component thatcross-links with the first cross-linkable component under reactionenabling conditions, and a hydrogel-forming component. The first andsecond cross-linkable components can cross-link to form a porous matrixhaving interstices, and the hydrogel forming component may be capable ofbeing hydrated to form a hydrogel to fill at least some of theinterstices. The hydrogel can include subunits that have sizes rangingfrom about 0.05 mm to about 5 mm when fully hydrated, that have anequilibrium swell ranging from about 400% to about 1300%, and thatdegrade in the tissue tract after from about 1 to about 120 days. Thefirst cross-linkable component can include multiple nucleophilic groupsand the second cross-linkable component can include multipleelectrophilic groups. In another aspect, embodiments of the presentinvention include a method for delivering a bioactive substance to atarget site in a patient's body. The method can include delivering acomposition in combination with the bioactive substance to the targetsite, where the composition includes a first cross-linkable component, asecond cross-linkable component that cross-links with the firstcross-linkable component under reaction enabling conditions, and ahydrogel-forming component. The first and second cross-linkablecomponents can cross-link to form a porous matrix having interstices,and the hydrogel forming component may be capable of being hydrated toform a hydrogel to fill at least some of the interstices. The hydrogelcan have subunits having sizes ranging from about 0.05 mm to about 5 mmwhen fully hydrated, an equilibrium swell ranging from about 400% toabout 1300%, and can degrade in the tissue tract after from about 1 toabout 120 days. In some cases, the first cross-linkable componentincludes a multiple nucleophilic groups and the second cross-linkablecomponent includes multiple electrophilic groups. The bioactivesubstance can be a hemostatic agent, such as thrombin.

In another aspect, embodiments of the present invention include a methodfor delivering a swellable composition to a target site in tissue. Themethod can include applying the composition to the target site, wherethe composition includes a first cross-linkable component, a secondcross-linkable component that cross-links with the first cross-linkablecomponent under reaction enabling conditions, and a hydrogel-formingcomponent. The first and second cross-linkable components can cross-linkto form a porous matrix having interstices, and the hydrogel formingcomponent can be capable of being hydrated to form a hydrogel to fill atleast some of the interstices. The hydrogel can include subunits thathave sizes ranging from about 0.05 mm to about 5 mm when fully hydrated,that have an equilibrium swell ranging from about 400% to about 1300%,and that degrade in the tissue tract after from about 1 to about 120days. The composition may be hydrated at less than its equilibrium swellupon application to the target site where it swells to an equilibriumswell value. In some aspects, the first cross-linkable componentincludes multiple nucleophilic groups and the second cross-linkablecomponent includes multiple electrophilic groups. In some aspects, thetarget site is in tissue can be muscle, skin, epithelial tissue, smooth,skeletal or cardiac muscle, connective or supporting tissue, nervetissue, ophthalmic and other sense organ tissue, vascular and cardiactissue, gastrointestinal organs and tissue, pleura and other pulmonarytissue, kidney, endocrine glands, male and female reproductive organs,adipose tissue, liver, pancreas, lymph, cartilage, bone, oral tissue,and mucosal tissue, and spleen and other abdominal organs. In someaspects, the target site includes a void region within the selectedtissue, such as a tissue divot, tissue tract, intravertebral space, orbody cavity. In some cases, the hydrogel has a degree of hydration inthe range from 50% to 95% of the hydration at equilibrium swell. In somecases the hydrogel includes a plasticizer, such as polyethylene glycol,sorbitol, or glycerol. The plasticizer may be present at from 0.1% byweight to 30% by weight of the composition of the hydrogel component. Insome cases, the hydrogel includes a cross-linked protein hydrogel. Theprotein can include gelatin, soluble collagen, albumin, hemoglobin,fibrogen, fibrin, casein, fibronectin, elastin, keratin, laminin, andderivatives and combinations thereof. In some cases, the hydrogelincludes a cross-linked polysaccharide. The polysaccharide can includeglycosaminoglycans, starch derivatives, cellulose derivatives,hemicellulose derivatives, xylan, agarose, alginate, and chitosan andcombinations thereof. In some cases, the hydrogel includes across-linked non-biologic polymer. The cross-linked non-biologic polymercan include polyacrylates, polymethacrylates, polyacrylamides, polyvinylresins, polyactide-glycolides, polcaprolactones, polyoxyethlenes, andcombinations thereof. In some cases, the hydrogel includes at least twocomponents selected from a group that includes cross-linked proteins,cross-linked polysaccharides, and cross-linked non-biologic polymers.The hydrogel can include a hydrogel polymer and a hydrogel cross-linkingagent. The hydrogel polymer and the hydrogel cross-linking agent mayhave been reacted under conditions which yield cross-linking of hydrogelpolymer molecules. In some cases, the hydrogel includes a molecularcross linked hydrogel polymer that has been produced by irradiation ofthe hydrogel under conditions which yield cross-linking of hydrogelpolymer molecules. In some cases, the hydrogel includes a molecularcross linked hydrogel that has been produced by reaction ofmonounsaturated and polyunsaturated hydrogel monomers under conditionswhich yield cross-linking of hydrogel polymer molecules.

In yet another aspect, embodiments of the present invention encompass amethod of forming a three dimensional synthetic polymer matrix. Themethod includes providing a first cross-linkable component containing mnucleophilic groups and a second cross-linkable component containing nelectrophilic groups. The electrophilic groups react with thenucleophilic groups to form covalent bonds therewith, m and n are eachgreater than or equal to two, and m+n is greater than or equal to five.The method also includes combining the first cross-linkable componentand the second cross-linkable component, adding a hydrogel formingcomponent to the first cross-linkable component and the secondcross-linkable component, and allowing the first cross-linkablecomponent and the second cross-linkable component to become cross-linkedto one another to form a three dimensional matrix. The method can alsoinclude contacting a first tissue surface and a second surface with thefirst cross-linkable component, the second cross linkable component, andthe hydrogel forming component. In some cases, the second surface is anative tissue surface. In some cases, the second surface is a non-nativetissue surface, such as a synthetic implant. The synthetic implant canbe a donor cornea, an artificial blood vessel, a heart valve, anartificial organ, a bond prosthesis, an implantable lenticule, avascular graft, a stent, or a stent/graft combination. In some cases,the first cross-linkable component, the second cross-linkable component,and the hydrogel forming component are each applied in powdered form atthe first tissue surface. In some cases, the first cross-linkablecomponent, the second cross-linkable component, and the hydrogel formingcomponent are each applied as a powder in a single combined mixed powderformulation at the first tissue surface. The mixed powder formulationcan include a protein and/or a polysaccharide. The first tissue surfacemay be on or in a hard tissue or a soft tissue. The first tissue surfacecan include, surround or be adjacent to a surgical site. The method canalso include closing the surgical site. In some cases, the mixed powderformulation includes collagen. In some cases, the mixed powderformulation includes a biologically active agent. In some aspects,embodiments of the present invention encompass a mixed powdercomposition that includes a first cross-linkable component in powderedform having multiple nucleophilic groups, a second cross-linkablecomponent in powdered form having multiple electrophilic groups, and ahydrogel forming component in powdered form. Under reaction-enablingconditions the first and second cross-linkable components are capable ofsubstantially immediate cross-linking

In a related aspect, the first cross-linkable component added to thesecond cross-linkable component provides a combined cross-linkablecomponent composition. The first cross-linkable component can be presentat a concentration in the range of about 0.5 to about 20 percent byweight of the combined cross-linkable component composition. In somecases, the second cross-linkable component can be present at aconcentration in the range of about 0.5 to about 20 percent by weight ofthe combined cross-linkable component composition. A weight ratio of thefirst cross-linkable component to the second cross-linkable componentcan be in the range from about 45% to about 55%. Relatedly, a weightratio of the first cross-linkable component to the second cross-linkablecomponent can be about 50%. In some cases, a weight ratio between thefirst and second cross-linkable components and the hydrogel-formingcomponent can be within a range from about 28% to about 42% w/w.Relatedly, a weight ratio between the first and second cross-linkablecomponents and the hydrogel-forming component can be within a range fromabout 20% to about 30% w/w. In some aspects, the first cross-linkablecomponent can be present at a concentration in the range of about 0.5 toabout 20 percent by weight of the combined cross-linkable componentcomposition. Relatedly, the second cross-linkable component can bepresent at a concentration in the range of about 0.5 to about 20 percentby weight of the combined cross-linkable component composition. A weightratio of the first cross-linkable component to the second cross-linkablecomponent can be in the range from about 45% to about 55%. Similarly, aweight ratio of the first cross-linkable component to the secondcross-linkable component can be about 50%.

In another aspect, embodiments of the present invention provide sealantmatrix composition kits. A kit can include, for example, a container anda mixed powder composition disposed within the container. Thecomposition can include a first cross-linkable component having multiplenucleophilic groups and a second cross-linkable component havingmultiple electrophilic groups. The first cross-linkable component, thesecond cross-linkable component, or both, may be in powdered form. Thekit can also include a hydrogel forming component in powdered form.Under reaction-enabling conditions the first and second cross-linkablecomponents may be capable of substantially immediate cross-linking. Insome cases, the container includes a syringe barrel and a syringeplunger. A kit can also include written instructions for applying themixed powder composition to a bleeding target site in a patient. In somecases, the mixed powder includes an active agent. The active agent mayinclude thrombin. In another aspect, a kit may include a collagen spongeor other suitable support, and a mixed powder composition fixed with asurface of the sponge or support. The composition can include a firstcross-linkable component having multiple nucleophilic groups and asecond cross-linkable component having multiple electrophilic groups.The first cross-linkable component, the second cross-linkable component,or both, may be in powdered form. The kit can also include a hydrogelforming component in powdered form. Under reaction-enabling conditionsthe first and second cross-linkable components may be capable ofsubstantially immediate cross-linking

For a fuller understanding of the nature and advantages of the presentinvention, reference should be had to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

The present invention includes but is not limited to:

A composition comprising:

a first cross-linkable component;a second cross-linkable component that cross-links with the firstcross-linkable component under reaction enabling conditions; anda hydrogel-forming component;wherein the first and second cross-linkable component cross-link to forma porous matrix having interstices, and wherein the hydrogel-formingcomponent is capable of being hydrated to form a hydrogel to fill atleast some of the interstices.

The composition of paragraph 31, wherein the first cross-linkablecomponent comprises multiple nucleophilic groups and the secondcross-linkable component comprises multiple electrophilic groups.

The composition of paragraph 31, wherein the first cross-linkablecomponent comprises a multi-nucleophilic polyalkylene oxide having mnucleophilic groups, and the second cross-linkable component comprises amulti-electrophilic polyalkylene oxide having n electrophilic groups,wherein m and n are each greater than or equal to two, and wherein m+nis greater than or equal to five.

The composition of paragraph 33, wherein n is two, and wherein m isgreater than or equal to three.

The composition of paragraph 34, wherein the multi-nucleophilicpolyalkylene oxide is tetrafunctionally activated.

The composition of paragraph 33, wherein m is two, and wherein n isgreater than or equal to three.

The composition of paragraph 36, wherein the multi-electrophilicpolyalkylene oxide is tetrafunctionally activated.

The composition of paragraph 33, wherein both the multi-nucleophilicpolyalkylene oxide and the multi-electrophilic polyalkylene oxide aretetrafunctionally activated.

The composition of paragraph 33, wherein the multi-nucleophilicpolyalkylene oxide further comprises two or more nucleophilic groupsselected from the group consisting of NH₂, —SH, —H, —PH₂, and—CO—NH—NH₂.

The composition of paragraph 33, wherein the multi-nucleophilicpolyalkylene oxide further comprises two or more primary amino groups.

The composition of paragraph 33, wherein the multi-nucleophilicpolyalkylene oxide further comprises two or more thiol groups.

The composition of paragraph 33, wherein the multi-nucleophilicpolyalkylene oxide is polyethylene glycol or a derivative thereof.

The composition of paragraph 42, wherein the polyethylene glycol furthercomprises two or more nucleophilic groups selected from the groupconsisting of a primary amino group and a thiol group.

The composition of paragraph 33, wherein the multi-electrophilicpolyalkylene oxide further comprises two or more electrophilic groupsselected from the group consisting of CO₂N(COCH₂)₂, —CO₂H, —CHO,—CHOCH₂, —N═C═O, —SO₂CH═CH₂, N(COCH)₂, and —S—S—(C₅H₄N).

The composition of paragraph 33, wherein the multi-electrophilicpolyalkylene oxide further comprises two or more succinimidyl groups.

The composition of paragraph 33, wherein the multi-electrophilicpolyalkylene oxide further comprises two or more maleimidyl groups.

The composition of paragraph 33, wherein the multi-electrophilicpolyalkylene oxide is a polyethylene glycol or a derivative thereof.

The composition of paragraph 33 further comprising a polysaccharide or aprotein.

The composition of paragraph 33 further comprising a polysaccharide,wherein the polysaccharide is a glycosaminoglycan.

The composition of paragraph 49, wherein the glycosaminoglycan isselected from the group consisting of hyaluronic acid, chitin,chondroitin sulfate A, chondroitin sulfate B, chondroitin sulfate C,keratin sulfate, keratosulfate, heparin, and derivatives thereof.

The composition of paragraph 33 further comprising a protein, whereinthe protein is collagen or a derivative thereof.

The composition of paragraph 33, wherein the multi-nucleophilicpolyalkylene oxide or the multi-electrophilic polyalkylene oxide, orboth the multi-nucleophilic polyalkylene oxide and themulti-electrophilic polyalkylene oxide, further comprise(s) a linkinggroup.

The composition of paragraph 33, wherein the multi-nucleophilicpolyalkylene oxide is given by the formula:

polymer-Q¹-X_(m)

-   -   and wherein the multi-electrophilic polyalkylene oxide is given        by the formula:

polymer-Q²-Y.

-   -   wherein X is an electrophilic group and Y is a nucleophilic        group;    -   wherein m and n are each 2 to 4;    -   wherein m+n≦5;    -   wherein each of Q¹ and Q² are linking groups selected from the        group consisting of —O—(CH₂)_(n′)—, —S—, —(CH₂)_(n′)—,        —NH—(CH₂)_(n′)—, —O₂C—NH—(CH₂)_(n′)—, —O₂C—(CH₂)_(n′)—,        —O₂C—CR¹H, and —O—R²—CO—NH;    -   wherein n′=1 to 10;    -   wherein R¹═—H, —CH₃, or —C₂H₅;    -   wherein R²═—CH₂— or —CO—NH—CH₂CH₂—; and    -   wherein Q¹ and Q² may be the same or different or may be absent.

The composition of paragraph 53, wherein Y is given by the formula:

—CO₂N(COCH₂)₂.

The composition of paragraph 53, wherein Y is given by the formula:

—N(COCH)₂.

The composition of paragraph 33, wherein the multi-nucleophilicpolykylene oxide or the multi-electrophilic polyalkylene oxide or boththe multi-nucleophilic polyalkylene oxide and the multi-electrophilicpolyalkylene oxide further comprise(s) a biodegradable group.

The composition of paragraph 56, wherein the biodegradable group isselected from the group consisting of lactide, glycolide,ε-caprolactone, poly(α-hydroxy acid), poly(amino acid), andpoly(anhydride).

The composition of paragraph 31, wherein the hydrogel forming componentis capable of being hydrated to form a fragmented biocompatible hydrogelthat comprises gelatin and will absorb water when delivered to a moisttissue target site, and wherein the hydrogel comprises subunits havingsizes ranging from about 0.01 mm to about 5 mm when fully hydrated andhas an equilibrium swell ranging from about 400% to about 5000%.

The composition of paragraph 58, wherein the hydrogel has an in vivodegradation time of less than one year.

The composition of any of paragraphs 58 and 59, wherein the hydrogel isat least partially hydrated with an aqueous medium comprising an activeagent.

The composition of paragraph 60, wherein the active agent is a clottingagent.

The composition of paragraph 61, wherein the clotting agent is thrombin.

A method for delivering an active agent to a patient, the methodcomprising administering to a target site on the patient an amount ofthe composition of paragraph 60.

A method for delivering a sealing agent to a patient, the methodcomprising administering to a bleeding target site an amount of thecomposition of paragraph 31 sufficient to inhibit bleeding.

A method for delivering thrombin to a patient, the method comprisingadministering to a bleeding target site an amount of the composition ofparagraph 62 sufficient to inhibit bleeding.

A composition comprising a multi-nucleophilic polyalkylene oxide, amulti-electrophilic polyalkylene oxide, and a hydrogel formingcomponent, wherein the multi-nucleophilic polyalkylene oxide furthercomprises at least one primary amino group and at least one thiol group,and wherein under reaction-enabling conditions the multi-nucleophilicpolyalkylene oxide and multi-electrophilic polyalkylene oxide arecapable of substantially immediate cross linking

A composition comprising a multi-nucleophilic polyalkylene oxide, amulti-electrophilic polyalkylene oxide, and a hydrogel formingcomponent, wherein the multi-nucleophilic polyalkylene oxide furthercomprises two or more thiol groups and the multi-electrophilicpolyalkylene oxide further comprises two or more electrophilic groupsselected from the group consisting of succinimidyl groups and maleimidylgroups, and wherein under reaction-enabling conditions themulti-nucleophilic polyalkylene oxide and multi-electrophilicpolyalkylene oxide are capable of substantially immediate cross linking

A composition comprising a multi-nucleophilic polyalkylene oxide, amulti-electrophilic polyalkylene oxide, and a hydrogel formingcomponent, wherein the multi-nucleophilic polyalkylene oxide furthercomprises two or more nucleophilic groups selected from the groupconsisting of primary amino groups and thiol groups, and themulti-electrophilic polyalkylene oxide further comprises two or moresuccinimidyl groups, and wherein under reaction-enabling conditions themulti-nucleophilic polyalkylene oxide and multi-electrophilicpolyalkylene oxide are capable of substantially immediate cross linking

A composition comprising a first polyethylene glycol comprising two ormore thiol groups, a second polyethylene glycol comprising two or moresuccinimidyl groups or maleimidyl groups, and a hydrogel formingcomponent, wherein the sum of the thiol groups and the succinimidyl ormaleimidyl groups is at least five, and wherein under reaction-enablingconditions the first polyethylene glycol and second polyethylene glycolare capable of substantially immediate cross linking

The composition of paragraph 69, wherein the first polyethylene glycolfurther comprises four thiol groups and the second polyethylene glycolfurther comprises four succinimidyl groups.

The composition of paragraph 69 further comprising a protein or apolysaccharide.

The composition of paragraph 69 further comprising a polysaccharide,wherein the polysaccharide is a glycosaminoglycan.

The composition of paragraph 72, wherein the glycosaminoglycan isselected from the group consisting of hyaluronic acid, chitin,chondroitin sulfate A, chondroitin sulfate B, chondroitin sulfate C,keratin sulfate, keratosulfate, heparin, and derivatives thereof.

The composition of paragraph 69 further comprising a protein, whereinthe protein is collagen or a derivative thereof.

A method for sealing a tissue tract, the method comprising at leastpartly filling a tissue tract with a composition comprising:

-   -   a first cross-linkable component;    -   a second cross-linkable component that cross-links with the        first cross-linkable component under reaction enabling        conditions; and    -   a hydrogel-forming component;    -   wherein the first and second cross-linkable components        cross-link to form a porous matrix having interstices, and the        hydrogel-forming component is capable of being hydrated to form        a hydrogel to fill at least some of the interstices, the        hydrogel comprising subunits having sizes ranging from about        0.05 mm to about 5 mm when fully hydrated, having an equilibrium        swell ranging from about 400% to about 1300%, and degrading in        the tissue tract after from about 1 to about 120 days.

The method of paragraph 75, wherein the first cross-linkable componentcomprises multiple nucleophilic groups and the second polymer comprisesmultiple electrophilic groups.

A method for inhibiting bleeding at a target site in a patient's body,the method comprising delivering a composition to the target site in anamount sufficient to inhibit bleeding, the composition comprising:

-   -   a first cross-linkable component;    -   a second cross-linkable component that cross-links with the        first cross-linkable component under reaction enabling        conditions; and    -   a hydrogel-forming component;    -   wherein the first and second cross-linkable components        cross-link to form a porous matrix having interstices, and the        hydrogel forming component is capable of being hydrated to form        a hydrogel to fill at least some of the interstices, the        hydrogel comprising subunits having sizes ranging from about        0.05 mm to about 5 mm when fully hydrated, having an equilibrium        swell ranging from about 400% to about 1300%, and degrading in        the tissue tract after from about 1 to about 120 days.

The method of paragraph 77, wherein the first cross-linkable componentcomprises multiple nucleophilic groups and the second cross-linkablecomponent comprises multiple electrophilic groups.

A method for delivering a bioactive substance to a target site in apatient's body, the method comprising delivering a composition incombination with the bioactive substance to the target site, thecomposition comprising:

-   -   a first cross-linkable component;    -   a second cross-linkable component that cross-links with the        first cross-linkable component under reaction enabling        conditions; and    -   a hydrogel-forming component;    -   wherein the first and second cross-linkable components        cross-link to form a porous matrix having interstices, and the        hydrogel forming component is capable of being hydrated to form        a hydrogel to fill at least some of the interstices, the        hydrogel comprising subunits having sizes ranging from about        0.05 mm to about 5 mm when fully hydrated, having an equilibrium        swell ranging from about 400% to about 1300%, and degrading in        the tissue tract after from about 1 to about 120 days.

The method of paragraph 79, wherein the first cross-linkable componentcomprises multiple nucleophilic groups and the second cross-linkablecomponent comprises multiple electrophilic groups.

A method as in paragraph 79, wherein the bioactive substance is ahemostatic agent.

A method as in paragraph 79, wherein the bioactive substance isthrombin.

A method for delivering a swellable composition to a target site intissue, said method comprising applying the composition to the targetsite, the composition comprising:

-   -   a first cross-linkable component;    -   a second cross-linkable component that cross-links with the        first cross-linkable component under reaction enabling        conditions; and    -   a hydrogel-forming component;    -   wherein the first and second cross-linkable components        cross-link to form a porous matrix having interstices, and the        hydrogel forming component is capable of being hydrated to form        a hydrogel to fill at least some of the interstices, the        hydrogel comprising subunits having sizes ranging from about        0.05 mm to about 5 mm when fully hydrated, having an equilibrium        swell ranging from about 400% to about 1300%, and degrading in        the tissue tract after from about 1 to about 120 days, the        composition being hydrated at less than its equilibrium swell        upon application to the target site where it swells to an        equilibrium swell value.

The method of paragraph 83, wherein the first cross-linkable componentcomprises multiple nucleophilic groups and the second cross-linkablecomponent comprises multiple electrophilic groups.

The method of paragraph 83, wherein the target site is in tissueselected from the group consisting of muscle, skin, epithelial tissue,connective or supporting tissue, nerve tissue, ophthalmic and othersense organ tissue, vascular and cardiac tissue, gastrointestinal organsand tissue, pleura and other pulmonary tissue, kidney, endocrine glands,male and female reproductive organs, adipose tissue, liver, pancreas,lymph, cartilage, bone, oral tissue, and mucosal tissue, and spleen andother abdominal organs.

The method of paragraph 85, wherein the target site is a void regionwithin the selected tissue.

The method of paragraph 86, wherein the void region is selected from thegroup consisting of tissue divots, tissue tracts, intravertebral spaces,and body cavities.

The method of paragraph 83, wherein the hydrogel has a degree ofhydration in the range from 50% to 95% of the hydration at equilibriumswell.

The method of paragraph 83, wherein the hydrogel comprises aplasticizer.

The method of paragraph 89, wherein the plasticizer is selected from thegroup consisting of polyethylene glycol, sorbitol, and glycerol.

The method of paragraph 89, wherein the plasticizer is present at from0.1% by weight to 30% by weight of the composition of the hydrogelcomponent.

A method as in any one of paragraphs 75-91, wherein the hydrogelcomprises a cross-linked protein hydrogel.

A method as in paragraph 92, wherein the protein is selected from thegroup consisting of gelatin, soluble collagen, albumin, hemoglobin,fibrogen, fibrin, casein, fibronectin, elastin, keratin, laminin, andderivatives and combinations thereof.

A method as in any one of paragraphs 75-91, wherein the hydrogelcomprises a cross-linked polysaccharide.

A method as in paragraph 94, wherein the polysaccharide is selected fromthe group consisting of glycosaminoglycans, starch derivatives,cellulose derivatives, hemicellulose derivatives, xylan, agarose,alginate, and chitosan and combinations thereof.

A method as in any one of paragraphs 75-91, wherein the hydrogelcomprises a cross-linked non-biologic polymer.

A method as in paragraph 96, wherein the cross-linked non-biologicpolymer selected from the group consisting of polyacrylates,polymethacrylates, polyacrylamides, polyvinyl resins,polyactide-glycolides, polcaprolactones, polyoxyethlenes, andcombinations thereof.

A method as in any one of paragraphs 75-91, wherein the hydrogelcomprises at least two components selected from the group consisting ofcross-linked proteins, cross-linked polysaccharides, and cross-linkednon-biologic polymers.

A method as in any one of paragraphs 75-91, wherein the hydrogelcomprises a hydrogel polymer and a hydrogel cross-linking agent, whereinthe hydrogel polymer and hydrogel cross-linking agent have been reactedunder conditions which yield cross-linking of hydrogel polymermolecules.

A method as in any one of paragraphs 75-91, wherein the hydrogelcomprises a molecular cross linked hydrogel polymer that has beenproduced by irradiation of the hydrogel under conditions which yieldcross-linking of hydrogel polymer molecules.

A method as in any one of paragraphs 75-91, wherein the hydrogelcomprises a molecular cross linked hydrogel that has been produced byreaction of monounsaturated and polyunsaturated hydrogel monomers underconditions which yield cross-linking of hydrogel polymer molecules.

A method of forming a three dimensional synthetic polymer matrixcomprising the steps of:

-   -   providing a first cross-linkable component containing m        nucleophilic groups and a second cross-linkable component        containing n electrophilic groups, wherein the electrophilic        groups react with the nucleophilic groups to form covalent bonds        therewith, wherein m and n are each greater than or equal to        two, and wherein m+n is greater than or equal to five;    -   combining the first cross-linkable component and the second        cross-linkable component;    -   adding a hydrogel forming component to the first cross-linkable        component and the second cross-linkable component;    -   allowing the first cross-linkable component and the second        cross-linkable component to become cross-linked to one another        to form a three dimensional matrix.

The method of paragraph 102, further comprising contacting a firsttissue surface and a second surface with the first cross-linkablecomponent, the second cross linkable component, and the hydrogel formingcomponent.

The method of paragraph 103, wherein the second surface is a nativetissue surface.

The method of paragraph 103, wherein the second surface is a non-nativetissue surface.

The method of paragraph 105, wherein the non-native tissue surface is asynthetic implant.

The method of paragraph 106, wherein the synthetic implant is selectedfrom the group consisting of a donor cornea, an artificial blood vessel,a heart valve, an artificial organ, a bond prosthesis, an implantablelenticule, a vascular graft, a stent, and a stent/graft combination.

The method of paragraph 102, wherein the first cross-linkable component,the second cross-linkable component, and the hydrogel forming componentare each applied in powdered form at the first tissue surface.

The method of paragraph 102, wherein the first cross-linkable component,the second cross-linkable component, and the hydrogel forming componentare each applied as a powder in a single combined mixed powderformulation at the first tissue surface.

The method of paragraph 109, wherein the mixed powder formulationfurther comprises a protein or a polysaccharide.

The method of paragraph 102, wherein the first tissue surface is on orin a hard tissue or a soft tissue.

The method of paragraph 102, wherein the first tissue surface comprises,surrounds or is adjacent to a surgical site, and wherein the methodfurther comprises the step of closing the surgical site.

The method of paragraph 102, wherein the mixed powder formulationfurther comprises collagen.

The method of paragraph 102, wherein the mixed powder formulationfurther comprises a biologically active agent.

A mixed powder composition comprising:

-   -   a first cross-linkable component comprising multiple        nucleophilic groups, the first cross-linkable component in        powdered form;    -   a second cross-linkable component comprising multiple        electrophilic groups, the second cross-linkable component in        powdered form; and    -   a hydrogel forming component in powdered form;    -   wherein under reaction-enabling conditions the first and second        cross-linkable components are capable of substantially immediate        cross-linking

The mixed powder composition of paragraph 115, wherein the firstcross-linkable component added to the second cross-linkable componentprovides a combined cross-linkable component composition, and the firstcross-linkable component is present at a concentration in the range ofabout 0.5 to about 20 percent by weight of the combined cross-linkablecomponent composition.

The mixed powder composition of paragraph 115, wherein the firstcross-linkable component added to the second cross-linkable componentprovides a combined cross-linkable component composition, and the secondcross-linkable component is present at a concentration in the range ofabout 0.5 to about 20 percent by weight of the combined cross-linkablecomponent composition.

The mixed powder composition of paragraph 115, wherein a weight ratio ofthe first cross-linkable component to the second cross-linkablecomponent is in the range from about 45% to about 55%.

The mixed powder composition of paragraph 115, wherein a weight ratio ofthe first cross-linkable component to the second cross-linkablecomponent is about 50%.

The mixed powder composition of paragraph 115, wherein a weight ratiobetween the first and second cross-linkable components and thehydrogel-forming component is within a range from about 28% to about 42%w/w.

The mixed powder composition of paragraph 115, wherein a weight ratiobetween the first and second cross-linkable components and thehydrogel-forming component is within a range from about 20% to about 30%w/w.

The mixed powder composition of paragraph 121, wherein the firstcross-linkable component added to the second cross-linkable componentprovides a combined cross-linkable component composition, and the firstcross-linkable component is present at a concentration in the range ofabout 0.5 to about 20 percent by weight of the combined cross-linkablecomponent composition.

The mixed powder composition of paragraph 121, wherein the firstcross-linkable component added to the second cross-linkable componentprovides a combined cross-linkable component composition, and the secondcross-linkable component is present at a concentration in the range ofabout 0.5 to about 20 percent by weight of the combined cross-linkablecomponent composition.

The mixed powder composition of paragraph 121, wherein a weight ratio ofthe first cross-linkable component to the second cross-linkablecomponent is in the range from about 45% to about 55%.

The mixed powder composition of paragraph 121, wherein a weight ratio ofthe first cross-linkable component to the second cross-linkablecomponent is about 50%.

A kit comprising:

-   -   a container; and    -   a mixed powder composition disposed within the container, the        composition comprising:    -   a first cross-linkable component comprising multiple        nucleophilic groups, the first cross-linkable component in        powdered form;    -   a second cross-linkable component comprising multiple        electrophilic groups, the second cross-linkable component in        powdered form; and    -   a hydrogel forming component in powdered form;    -   wherein under reaction-enabling conditions the first and second        cross-linkable components are capable of substantially immediate        cross-linking

The kit of paragraph 126, wherein the container comprises a syringebarrel and a syringe plunger.

The kit of paragraph 126, further comprising written instructions forapplying the mixed powder composition to a bleeding target site in apatient.

The kit of paragraph 126, wherein the mixed powder further comprises anactive agent.

The kit of paragraph 129, wherein the active agent comprises thrombin.

A kit comprising:

-   -   a collagen sponge; and    -   a mixed powder composition fixed with a surface of the sponge,        the mixed powder composition comprising:    -   a first cross-linkable component comprising multiple        nucleophilic groups, the first cross-linkable component in        powdered form;    -   a second cross-linkable component comprising multiple        electrophilic groups, the second cross-linkable component in        powdered form; and    -   a hydrogel forming component in powdered form;    -   wherein under reaction-enabling conditions the first and second        cross-linkable components are capable of substantially immediate        cross-linking

A composition for the manufacture of a medicament comprising:

-   -   a first cross-linkable component;    -   a second cross-linkable component that cross-links with the        first cross-linkable component under reaction enabling        conditions; and    -   a hydrogel-forming component;    -   wherein the first and second cross-linkable component cross-link        to form a porous matrix having interstices, and wherein the        hydrogel-forming component is capable of being hydrated to form        a hydrogel to fill at least some of the interstices.

The composition of paragraph 132, wherein the first cross-linkablecomponent comprises multiple nucleophilic groups and the secondcross-linkable component comprises multiple electrophilic groups.

The composition of paragraph 133, wherein the first cross-linkablecomponent comprises a multi-nucleophilic polyalkylene oxide having mnucleophilic groups, and the second cross-linkable component comprises amulti-electrophilic polyalkylene oxide having n electrophilic groups,wherein m and n are each greater than or equal to two, and wherein m+nis greater than or equal to five.

The composition of paragraph 134, wherein n is two, and wherein m isgreater than or equal to three.

The composition of paragraph 135, wherein the multi-nucleophilicpolyalkylene oxide is tetrafunctionally activated.

The composition of paragraph 134, wherein m is two, and wherein n isgreater than or equal to three.

The composition of paragraph 137, wherein the multi-electrophilicpolyalkylene oxide is tetrafunctionally activated.

The composition of paragraph 134, wherein both the multi-nucleophilicpolyalkylene oxide and the multi-electrophilic polyalkylene oxide aretetrafunctionally activated.

The composition of paragraph 134, wherein the multi-nucleophilicpolyalkylene oxide further comprises two or more nucleophilic groupsselected from the group consisting of NH₂, —SH, —H, —PH₂, and—CO—NH—NH₂.

The composition of paragraph 134, wherein the multi-nucleophilicpolyalkylene oxide further comprises two or more primary amino groups.

A composition comprising:

-   -   a collagen sponge comprising native collagen fibers; and    -   a mixed powder composition fixed with a surface of the sponge,        the mixed powder composition comprising:    -   a first cross-linkable component comprising multiple        nucleophilic groups, the first cross-linkable component in        powdered form and comprising about 10% of the mixed powder;    -   a second cross-linkable component comprising multiple        electrophilic groups, the second cross-linkable component in        powdered form and comprising about 10% of the mixed powder; and    -   a hydrogel forming component in powdered form, comprising about        80% of the mixed powder;    -   wherein under reaction-enabling conditions the first and second        cross-linkable components are capable of substantially immediate        cross-linking to form a porous matrix having interstices, and        the hydrogel-forming component is capable of being hydrated to        form a hydrogel to fill at least some of the interstices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a first cross-linkable component according to someembodiments of the present invention.

FIG. 2 illustrates a second cross-linkable component according to someembodiments of the present invention.

FIG. 3 shows the formation of a crosslinked matrix composition from ahydrophilic polymer according to some embodiments of the presentinvention.

FIG. 4 shows the formation of a crosslinked matrix composition from ahydrophobic polymer according to some embodiments of the presentinvention.

FIG. 5 illustrates a hydrogel-forming component subunit according tosome embodiments of the present invention.

FIG. 6 illustrates the correlation between percent swell and the percentsolids of a fragmented crosslinked polymeric gel useful as ahydrogel-forming component in a sealant composition according to someembodiments of the present invention.

FIGS. 7A-E illustrate the application of a sealant matrix composition totreat a splenic artery puncture according to embodiments of the presentinvention.

FIGS. 8A-E illustrate the application of a sealant matrix composition totreat a hepatic resection according to embodiments of the presentinvention.

FIG. 9 illustrates the processing and packaging of a sealant matrixcomposition according to embodiments of the present invention.

FIG. 10 illustrates the processing and packaging of a sealant matrixcomposition according to embodiments of the present invention.

FIG. 11 illustrates the effect of PEG concentration on gel strength,according to embodiments of the present invention.

FIG. 12 illustrates the effect of PEG concentration on swelling ratio,according to embodiments of the present invention.

FIG. 13 illustrates the effect of PEG concentration on swelling ratio,according to embodiments of the present invention.

FIG. 14 illustrates the effect of PEG concentration on swelling ratio,according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to some embodiments, the present invention provides drysealant matrix compositions for the achievement of hemostasis or otherfluid containment in an in vivo context by sealing a tissue breach ordefect. The compositions of some embodiments of the invention comprisefirst and second cross-linkable components and at least onehydrogel-forming component, in a dry composition suitable for applyingto a tissue of a vertebrate to facilitate fluid containment. The firstand second components in the compositions of the invention react underin-vivo conditions to form a cross-linked matrix, while thehydrogel-forming component rapidly absorbs the biological fluid comingthrough the tissue breach, as well as strengthening the resultantphysical sealant matrix barrier formed as the first and secondcomponents cross-link. As described in this application, “sealant matrixcompositions” may refer to compositions of the invention beforeapplication to the tissue site in vivo, and “sealant matrix barrier” mayrefer to the resulting matrix barrier after the compositions of theinvention contact biological fluids and the first and second componentscross-link to form a porous cross-linked matrix containing the hydrogel.Sealant matrix compositions may be produced in a variety of formats,including powders, cakes, pads, and the like. Cake embodiments includesealant matrix composition powder samples that have been heated or bakedto form an aggregate body. Pad embodiments include sealant matrixcomposition powder samples that have been placed on a sponge such as acollagen sponge or other support, which is then baked to created asolidified powder that is fused to the sponge or support.

Although the present invention may be used to contain non-bloodbiological fluids (e.g., lymph or spinal fluid), the sealant matrixformed by the compositions of some embodiments of the present inventionmay also be called a “hemostatic matrix,” as this is a primary usedescribed herein.

In addition to providing rapid hemostasis and a barrier with highadherence to surrounding tissues, the sealant matrix of some embodimentsof the present invention has several advantages over previouslydisclosed materials used to achieve hemostasis. First, the sealantmatrix of some embodiments of the present invention may be used underconditions where the tissue breach is quite wet (e.g., rapidly oozing orspurting arterial bleeds, such as abrasive or sharp trauma to aninternal organ). In comparison, many compositions currently marketed forhemostasis require a relatively dry site for proper adherence of thecomposition and the maintenance of hemostasis. For example, in somecases certain PEG mixtures may be placed in a rapidly bleeding site,however it is likely that they could be washed away. Similarly, in somecases certain gelatin compositions could hydrate in a rapidly bleedingsite, however it is likely that they could have difficulty remaining atthe site. Advantageously, it has been discovered that preparations whichinclude a first cross-linkable component, a second cross-linkablecomponent, and a hydrogel-forming component can provide a material thatin reaction enabling conditions remains immobilized even withsubstantial bleeding to form a mechanically stable clot-like material tostaunch the bleeding. Second, the sealant matrix of some embodiments ofthe present invention functions by physically sealing the tissue breach,without reliance on any endogenous clotting capacity of the vertebrate.Thus, the sealant matrix can be utilized on vertebrates with lowfibrinogen concentration in their blood, or even with blood substitutesthat contain no fibrinogen. For example, when first and secondcross-linkable components are combined with a hydrogel forming componentand applied to a bleeding surface, a synergistic interaction between thecross-linkable components and the hydrogel forming component can occur.According to some embodiments, the first and second cross-linkablecomponents can, in the presence of they hydrogel forming component,react and cross-link at the bleeding target site to form a relativelyrigid framework. Relatedly, the hydrogel forming component can fill inthe relatively rigid framework and mediate the formation of a physicalseal.

In accordance with some embodiments of the present invention, sealantmatrix compositions can be prepared mixing a first cross-linkablecomponent with a second cross-linkable component and a hydrogel-formingcomponent under conditions in which the first and second cross-linkablecomponents do not cross-link (i.e., lack of moisture, proper pH,temperature, etc.). Upon contact with the biological fluid, or in otherreaction enabling conditions, the cross-linkable first and secondcomponents cross-link to form a porous matrix having interstices, andthe hydrogel-forming component is hydrated to form a hydrogel filling atleast some of the interstices. Optionally, the cross-linkable componentsmay also cross-link with the hydrogel-forming component and/orsurrounding tissues.

I. SEALANT MATRIX CROSS-LINKABLE COMPONENTS

Often, the first cross-linkable component contains two or morenucleophilic groups and the second cross-linkable component contains twoor more electrophilic groups capable of covalently binding with thenucleophilic groups on the first cross-linkable component. The first andsecond components can cross-link to form a porous matrix. Exemplaryfirst and second components and porous matrices are described in U.S.Pat. Nos. 5,874,500; 6,166,130; 6,312,725; 6,328,229; and 6,458,889; thecontents of which are hereby incorporated by reference.

The first and second components are typically selected to benon-immunogenic and, as such, may not require a “skin test” prior tostarting treatment. Further, these components and the hydrogel-formingcomponent may be selected to resist enzymatic cleavage by matrixmetalloproteinases (e.g., collagenase) to provide greater long-termpersistence in vivo than currently available collagen compositions.Alternatively, the first and second components and the hydrogel-formingcomponents may be selected to be eliminated or resorbed during woundhealing in order to avoid the formation of fibrous tissue around thesealant matrix in vivo.

In one embodiment, the first component may be a synthetic polymercontaining multiple nucleophilic groups (represented below as “X”) whichcan react with a second component synthetic polymer containing multipleelectrophilic groups (represented below as “Y”), resulting in acovalently bound polymer network, as follows:

polymer-X_(m)+polymer-Y_(n)→polymer-Z-polymer

whereinm≧2, n≧2, and m+n≧5;X═—NH₂, —SH, —OH, —PH₂, —CO—NH—NH₂, etc., and can be the same ordifferent;Y═—CO₂N(COCH₂)₂, —CO₂H, —CHO, —CHOCH₂, —N═C═O, SO₂ CH═CH₂, —N(COCH)₂),—S—S—(C₅H₄N), etc., and can be the same or different; andZ=functional group resulting from the union of a nucleophilic group (X)and an electrophilic group (Y).

As noted above, X and Y may be the same or different, i.e., the firstcomponent may have two different nucleophilic groups and/or the secondcomponent may have two different electrophilic groups. An exemplaryfirst component polymer or first cross-linkable component is illustratedin FIG. 1. An exemplary second component polymer or secondcross-linkable component is illustrated in FIG. 2.

The backbone of the first and second component polymers can be analkylene oxide, particularly, ethylene oxide, propylene oxide, andmixtures thereof. Examples of difunctional alkylene oxides can berepresented by:

X-polymer-X Y-polymer-Y

wherein X and Y are as defined above, and the term “polymer”represents-(CH₂CH₂O)_(n)— or —(CH(CH₃)CH₂O)_(n)— or—(CH₂CH₂O)_(n)—(CH(CH₃)CH₂O)_(n)—.

The functional group X or Y is commonly coupled to the polymer backboneby a linking group (represented below as “Q”), many of which are knownor possible. Although the components of the invention have two or morefunctional groups, the examples below show only one functional group andthe resulting cross-linking for the sake of simplicity. There are manyways to prepare the various functionalized polymers, some of which arelisted below:

polymer-Q¹-X + polymer-Q²-Y → polymer-Q¹-Z-Q²-polymer wherein Q = wholestructure = —O—(CH₂)_(n)— polymer-O—(CH₂)_(n)—X (or Y) —S—(CH₂)_(n)—polymer-S—(CH₂)_(n)—X (or Y) —NH—(CH₂)_(n)— polymer-NH—(CH₂)_(n)—X (orY) —O₂C—NH—(CH₂)_(n)— polymer-O O₂C—NH—(CH₂)_(n)—X (or Y)—O₂C—(CH₂)_(n)— polymer-O₂C—(CH₂)_(n)—X (or Y) —O₂C—CR¹H—polymer-O₂C—CRH—X (or Y) —O—R²—CO—NH— polymer-O—R—CO—NH—X (or Y)whereinn=1-10 in each case;

R¹═H, CH₃, C₂H₅, . . . C_(p)H_(2p+1); R²═CH₂, CO—NH—CH₂CH₂.

Q¹ and Q² may be the same or different.

For example, when Q²═OCH₂CH₂ (there is no Q₁ in this case);Y═—CO₂N(COCH₂)₂; and X═—NH₂, —SH, or —OH, the resulting reactions and Zgroups would be as follows:

polymer-NH₂+polymer-OCH₂CH₂CO₂—N(COCH₂)₂→—NH—OCH₂CH₂CO-polymer (amide)

polymer-SH+polymer-OCH₂CH₂CO₂—N(COCH₂)₂→—S—OCH₂CH₂CO-polymer (thioester)

polymer-OH+polymer-OCH₂CH₂CO₂—N(COCH₂)₂→-O—OCH₂CH₂CO-polymer (ester)

An additional group, represented below as “D”, can be inserted betweenthe polymer and the linking group to increase degradation of thecrosslinked polymer composition in vivo, for example, for use in drugdelivery applications:

polymer-D-Q-X+polymer-D-Q-Y→polymer-D-Q-Z-Q-D-polymer-

Some useful biodegradable groups “D” include lactide, glycolide,ε-caprolactone, poly(α-hydroxy acid), poly(amino acids),poly(anhydride), and various di- or tripeptides.

A. First and Second Components with Polymer Backbones

As noted above, in order to prepare the compositions of the presentinvention, it is useful to provide a first component polymer containingtwo or more nucleophilic groups, such as primary amino groups or thiolgroups, and a second component polymer containing two or moreelectrophilic groups capable of covalently binding with the nucleophilicgroups on the first component polymer. The first and second componentpolymers can be synthetic.

As used with respect to first and second component polymers, the term“polymer” refers inter alia to polyalkyls; di-, tri-, oligo-, andpolyamino acids; and tri-, oligo-, or polysaccharides.

As used with respect to first and second component polymers, the term“synthetic polymer” encompasses polymers that are not naturallyoccurring and that are produced via chemical synthesis. As such,naturally occurring proteins such as collagen and naturally occurringpolysaccharides such as hyaluronic acid may be excluded. Syntheticcollagen, and synthetic hyaluronic acid, and their derivatives, areincluded. Synthetic polymers containing either nucleophilic orelectrophilic groups encompass “multifunctionally activated syntheticpolymers”. The term “multifunctionally activated” (or, simply,“activated”) can refer to synthetic polymers which have, or have beenchemically modified to have, two or more nucleophilic or electrophilicgroups which are capable of reacting with one another (i.e., thenucleophilic groups react with the electrophilic groups) to formcovalent bonds. Types of multifunctionally activated synthetic polymersinclude difunctionally activated, tetrafunctionally activated, andstar-branched polymers.

Multifunctionally activated synthetic polymers for use in the presentinvention often contain at least two, or at least three, functionalgroups in order to form a three-dimensional crosslinked network withsynthetic polymers containing multiple nucleophilic groups (i.e.,“multi-nucleophilic polymers”). In other words, they are typically atleast difunctionally activated, or trifunctionally or tetrafunctionallyactivated. If the first synthetic polymer is a difunctionally activatedsynthetic polymer, the second synthetic polymer typically contains threeor more functional groups in order to obtain a three-dimensionalcrosslinked network. Both the first and the second component polymer maycontain at least three functional groups.

B. First Component Polymer

First component polymers containing multiple nucleophilic groups arealso referred to generically herein as “multi-nucleophilic polymers”.For use in the present invention, multi-nucleophilic polymers oftencontain at least two, or at least three, nucleophilic groups. If asynthetic polymer containing only two nucleophilic groups is used, asynthetic polymer containing three or more electrophilic groups willoften be used in order to obtain a three-dimensional crosslinkednetwork.

Multi-nucleophilic polymers for use in the compositions and methods ofthe present invention include synthetic polymers that contain, or havebeen modified to contain, multiple nucleophilic groups such as primaryamino groups and thiol groups. Such multi-nucleophilic polymers caninclude: (i) synthetic polypeptides that have been synthesized tocontain two or more primary amino groups or thiol groups; and (ii)polyethylene glycols that have been modified to contain two or moreprimary amino groups or thiol groups. In general, reaction of a thiolgroup with an electrophilic group tends to proceed more slowly thanreaction of a primary amino group with an electrophilic group.

Multi-nucleophilic polypeptides can be synthetic polypeptides that havebeen synthesized to incorporate amino acids containing primary aminogroups (such as lysine) and/or amino acids containing thiol groups (suchas cysteine). For instance, the first component polymer can be adilysine, trilysine, quatralysine, pentalysine, or a dicysteine,tricysteine, quatracysteine, pentacystein, or oligopeptides orpolypeptides comprising two or more lysines or cysteines and other aminoacids (e.g., glycine, alanine,), preferably non-hydrophobic amino acids.Poly(lysine), a synthetically produced polymer of the amino acid lysine(145 MW), is often used. Poly(lysine)s have been prepared havinganywhere from 6 to about 4,000 primary amino groups, corresponding tomolecular weights of about 870 to about 580,000. Poly(lysine)s ofvarying molecular weights are commercially available from PeninsulaLaboratories, Inc. (Belmont, Calif.).

Polyethylene glycol can be chemically modified to contain multipleprimary amino or thiol groups according to methods set forth, forexample, in Chapter 22 of Poly(ethylene Glycol) Chemistry: Biotechnicaland Biomedical Applications, J. Milton Harris, ed., Plenum Press, N.Y.(1992). Polyethylene glycols which have been modified to contain two ormore primary amino groups are referred to herein as “multi-amino PEGs”.Polyethylene glycols which have been modified to contain two or morethiol groups are referred to herein as “multi-thiol PEGs”. As usedherein, the term “polyethylene glycol(s)” includes modified and orderivatized polyethylene glycol(s).

Various forms of multi-amino PEG are commercially available fromShearwater Polymers (Huntsville, Ala.) and from Texaco Chemical Company(Houston, Tex.) under the name “Jeffamine”. Multi-amino PEGs useful inthe present invention include Texaco's Jeffamine diamines (“D” series)and triamines (“T” series), which contain two and three primary aminogroups per molecule, respectively.

Polyamines such as ethylenediamine (H₂N—CH₂CH₂—NH₂),tetramethylenediamine (H₂N—(CH₂)₄—NH₂), pentamethylenediamine(cadaverine) (H₂N—(CH₂)₅—NH₂), hexamethylenediamine (H₂N—(CH₂)₆—NH₂),bis(2-hydroxyethyl)amine (HN—(CH₂CH₂OH)₂), bis(2)aminoethyl)amine(HN—(CH₂CH₂NH₂)₂), and tris(2-aminoethyl)amine (N—(CH₂CH₂NH₂)₃) may alsobe used as the first component synthetic polymer containing multiplenucleophilic groups.

C. Second Component Polymer

Second component polymers containing multiple electrophilic groups arealso referred to herein as “multi-electrophilic polymers.” For use inthe present invention, the multi-electrophilic polymers often contain atleast two, or at least three, electrophilic groups in order to form athree-dimensional crosslinked network with multi-nucleophilic polymers.

Multi-electrophilic polymers for use in the compositions of theinvention can be polymers which contain two or more succinimidyl groupscapable of forming covalent bonds with nucleophilic groups on othermolecules. Succinimidyl groups are highly reactive with materialscontaining primary amino (—NH₂) groups, such as multi-amino PEG,poly(lysine), or collagen. Succinimidyl groups are slightly lessreactive with materials containing thiol (—SH) groups, such asmulti-thiol PEG or synthetic polypeptides containing multiple cysteineresidues.

As used herein, the term “containing two or more succinimidyl groups” ismeant to encompass polymers which are commercially available containingtwo or more succinimidyl groups, as well as those that are chemicallyderivatized to contain two or more succinimidyl groups. As used herein,the term “succinimidyl group” is intended to encompass sulfosuccinimidylgroups and other such variations of the “generic” succinimidyl group.The presence of the sodium sulfite moiety on the sulfosuccinimidyl groupserves to increase the solubility of the polymer.

D. Hydrophilic Polymers for Use as First or Second Component Backbones

Hydrophilic polymers and, in particular, various polyethylene glycols,can be used in the first and second component polymer backbonesaccording to some embodiments of the present invention. As used herein,the term “PEG” encompasses polymers having the repeating structure(OCH₂CH₂)_(n).

A structure for a tetrafunctionally activated form of PEG is shown inFIG. 3, as is a generalized reaction product obtained by reacting atetrafunctionally activated PEG with a multi-amino PEG. As depicted inthe figure, the succinimidyl group is a five-member ring structurerepresented as —N(COCH₂)₂. In FIG. 3, the symbol ̂̂̂ denotes an openlinkage.

Embodiments include the reaction of tetrafunctionally activated PEGsuccinimidyl glutarate, referred to herein as SG-PEG, with multi-aminoPEG, and the reaction product obtained thereby. Another activated formof PEG is referred to as PEG succinimidyl propionate (SE-PEG).Embodiments include tetrafunctionally activated SE-PEG and the reactionproduct obtained by reacting it with multi-amino PEG. In someembodiments there are three repeating CH₂ groups on either side of thePEG. Further embodiments encompass a conjugate which includes an “ether”linkage which is less subject to hydrolysis. This is distinct from theconjugate shown in FIG. 3, wherein an ester linkage is provided. Theester linkage is subject to hydrolysis under physiological conditions.Other functionally activated forms of polyethylene glycol arecontemplated by embodiments of the present invention, as are theconjugates formed by reacting tetrafunctionally activated PEGs with amulti-amino PEG. In some embodiments, a conjugate includes both an etherand an amide linkage. These linkages are stable under physiologicalconditions.

Another functionally activated form of PEG is referred to as PEGsuccinimidyl succinamide (SSA-PEG). Embodiments include thetetrafunctionally activated form of this compound and the reactionproduct obtained by reacting it with multi-amino PEG. These and relatedcompounds may also be used in compositions according to embodiments ofthe invention. Embodiments also encompass a conjugate which includes an“amide” linkage which, like the ether linkage previously described, isless subject to hydrolysis and is therefore more stable than an esterlinkage. Yet another activated form of PEG is provided in a compoundembodiment referred to as PEG succinimidyl carbonate (SC-PEG).Embodiments include tetrafunctionally activated SC-PEG and the conjugateformed by reacting it with multi-amino PEG.

As discussed above, activated polyethylene glycol derivatives for use inembodiments of the invention can contain succinimidyl groups as thereactive group. However, different activating groups can be attached atsites along the length of the PEG molecule. For example, PEG can bederivatized to form functionally activated PEG propion aldehyde (A-PEG).Embodiments encompass the tetrafunctionally activated form as well asthe conjugate formed by the reaction of A-PEG with multi-amino PEG. Thelinkage may be referred to as a —(CH₂)_(m)—NH— linkage, where m=1-10.

Yet another form of activated polyethylene glycol is functionallyactivated PEG glycidyl ether (E-PEG). Embodiments encompass thetetrafunctionally activated compound, as well as the conjugate formed byreacting such with multi-amino PEG. Another activated derivative ofpolyethylene glycol is functionally activated PEG-isocyanate (1-PEG).Embodiments include conjugate formed by reacting such with multi-aminoPEG. Another activated derivative of polyethylene glycol is functionallyactivated PEG-vinylsulfone (V-PEG). Embodiments include the conjugateformed by reacting such with multi-amino PEG.

Multifunctionally activated polyethylene glycols for use in compositionsand other embodiments of the present invention can include polyethyleneglycols containing succinimidyl groups, such as SG-PEG and SE-PEG, whichcan be in trifunctionally or tetrafunctionally activated form. Many ofthe activated forms of polyethylene glycol described above are nowavailable commercially from Shearwater Polymers, Huntsville, Ala., andUnion Carbide, South Charleston, W.Va.

E. Derivatization of the First and Second Component Polymers to ContainFunctional Groups

Certain polymers, such as polyacids, can be derivatized to contain twoor more functional groups, such as succinimidyl groups. Polyacids foruse in the present invention include, without limitation,trimethylolpropane-based tricarboxylic acid, di(trimethylolpropane)-based tetracarboxylic acid, heptanedioic acid, octanedioic acid(suberic acid), and hexadecanedioic acid (thapsic acid). Many of thesepolyacids are commercially available from DuPont Chemical Company.

According to a general method, polyacids can be chemically derivatizedto contain two or more succinimidyl groups by reaction with anappropriate molar amount of N-hydroxysuccinimide (NHS) in the presenceof N,N′-dicyclohexylcarbodiimide (DCC).

Polyalcohols such as trimethylolpropane and di(trimethylol propane) canbe converted to carboxylic acid form using various methods, then furtherderivatized by reaction with NHS in the presence of DCC to producetrifunctionally and tetrafunctionally activated polymers, respectively,as described in U.S. application Ser. No. 08/403,358. Polyacids such asheptanedioic acid (HOOC—(CH₂)₂—COOH), octanedioic acid(HOOC—(CH₂)₂—COOH), and hexadecanedioic acid (HOOC—(CH₂)₁₄—COOH) arederivatized by the addition of succinimidyl groups to producedifunctionally activated polymers.

Polyamines such as ethylenediamine (H₂N—CH₂CH₂—NH₂),tetramethylenediamine (H₂N—(CH₂)₄—NH₂), pentamethylenediamine(cadaverine) (H₂N—(CH₂)₅—NH₂), hexamethylenediamine (H₂N—(CH₂)₆—NH₂),bis(2-hydroxyethyl)amine (HN—(CH₂CH₂OH)₂), bis(2)aminoethyl)amine(HN—(CH₂CH₂NH₂)₂), and tris(2-aminoethyl)amine (N—(CH₂CH₂NH₂)₃) can bechemically derivatized to polyacids, which can then be derivatized tocontain two or more succinimidyl groups by reacting with the appropriatemolar amounts of N-hydroxysuccinimide in the presence of DCC, asdescribed in U.S. application Ser. No. 08/403,358. Many of thesepolyamines are commercially available from DuPont Chemical Company.

In some embodiments, a first cross-linkable component (e.g. multi-aminoPEG) is present at a concentration in the range of about 0.5 to about 20percent by weight of the total cross-linkable component composition, anda second cross-linkable component is present at a concentration in therange of about 0.5 to about 20 percent by weight of the totalcross-linkable component composition. For example, a finalcross-linkable component composition having a total weight of 1 gram(1000 milligrams) could contain between about 5 to about 200 milligramsof the first cross-linkable component (e.g. multi-amino PEG), andbetween about 5 to about 200 milligrams of the second cross-linkablecomponent.

In some embodiments, the weight ratio of the first cross-linkablecomponent to the second cross-linkable component is in the range fromabout 20% to about 80%. In related embodiments, this ratio is in therange from about 45% to about 55%. In some cases, the ratio is about50%. The weight ratio is determined on the basis of a gel strength test.The first cross-linkable component and the second cross-linkablecomponent may have the same molecular weight.

II. HYDROGEL-FORMING COMPONENTS FOR USE IN THE SEALANT MATRIXCOMPOSITION

Hydrogel-forming components for use according to the present inventioncan include resorbable biocompatible molecular cross-linked gels andhydrogels as discussed in U.S. Pat. Nos. 4,640,834; 5,209,776;5,292,362; 5,714,370; 6,063,061; and, 6,066,325, which are herebyincorporated by reference. Materials made by the techniques described inthese patents are commercially available under the FLOSEAL trademarkfrom the Baxter Healthcare Corporation, in a kit for mixture withthrombin solution for use as a hemostatic agent. Alternatively, anyhydratable cross-linked polymers may be used as hydrogel-formingcomponents in the invention. For example, alginates, agaroses, gelatins(e.g., SURGIFOAM™ powder), or other synthetic, carbohydrate orprotein-based hydratable cross-linked polymers may be used. The primarycharacteristics of useful hydrogel-forming components arebiocompatibility, rapid absorption and retention of fluid. Thus,although polyacrylamide may be used as a hydrogel-forming component inthe invention, it would be less preferred due to its poorbiocompatibility in many internal applications. Often, the hydratablecross-linked polymers for use as the hydrogel-forming component have aparticle size of about 70 to about 300 microns, and a pH of about 6.8 toabout 9.5. Hydrogel-forming components can provide mechanical stabilityto the first and second cross-linkable components, particularly when asealant matrix is subject to forces, pressures, or dilutions.

In some embodiments, the weight ratio between the first and secondcross-linkable components, and the hydrogel-forming component, is withina range from about 28% to about 42% w/w. In some cases, a compositionmay contain a concentration of combined first and second cross-linkablecomponents that is about 5% to about 75% of the total mass of thecomposition, and a concentration of hydrogel forming component that isabout 95% to about 25% of the total mass of the composition. Relatedly,a composition may contain a concentration of combined first and secondcross-linkable components that is about 5% to about 40% of the totalmass of the composition, and a concentration of hydrogel formingcomponent that is about 95% to about 60% of the total mass of thecomposition. Similarly, a composition may contain a concentration ofcombined first and second cross-linkable components that is about 10% toabout 30% of the total mass of the composition, and a concentration ofhydrogel forming component that is about 90% to about 70% of the totalmass of the composition. For example, a composition may contain about20% combined first and second cross-linkable components, and about 80%hydrogel forming component. In some embodiments, a combined first andsecond cross-linkable component composition can have a fixed weightratio of 50:50%, and the w/w ratio of the combined first and secondcross-linkable component composition to the hydrogel-forming componentcan be with a range from about 20% to about 30%. The w/w ratio of thecombined first and second cross-linkable component composition to thehydrogel-forming component can be selected based on a gelstrength/adherence test. The hydrogel-forming component can act as anabsorbent to provide a semi-dry surface for the first and secondcross-linkable components to polymerize. Embodiments of the presentinvention encompass dry sealant matrix composition kits that includecross-linkable components and hydrogel-forming components in amountsaccording to these ratios.

According to some embodiments, the term “biocompatible” refers tomaterials that meet the criteria in standard # ISO 10993-1 promulgatedby the International Organization for Standardization (NAMSA, Northwood,Ohio). According to some embodiments, the term “resorbable” refers tocompositions that degrade or solubilize, when placed directly into atarget site in a patient's body (and not protected within an implantdevice such as a breast implant), over a time period of less than oneyear, usually from 1 to 120 days. Protocols for measuring resorption anddegradation are known. According to some embodiments, the term“molecular cross-linked” refers to materials that include polymermolecules (i.e. individual chains) which are attached by bridgescomposed of either an element, a group, or a compound, where thebackbone atoms of the polymer molecules are joined by primary chemicalbonds. Cross-linking may be effected in a variety of ways, as will bedescribed in greater detail below.

According to some embodiments, the term “hydrogel” encompassescompositions that include a single phase aqueous colloid in which abiologic or non-biologic polymer, as defined in more detail below,absorbs water or an aqueous buffer. A hydrogel can comprise multiplesub-networks, where each sub-network is a molecular cross-linkedhydrogel having dimensions which depend on the degree of hydration andare within the ranges set forth above. Often, the hydrogels will havelittle or no free water, i.e., water cannot be removed from the hydrogelby simple filtration.

“Percent swell” can be defined as the dry weight is subtracted from thewet weight, divided by the dry weight and multiplied by 100, where wetweight is measured after a wetting agent has been removed as completelyas possible from the exterior of the material, e.g., by filtration, andwhere dry weight is measured after exposure to an elevated temperaturefor a time sufficient evaporate the wetting agent, e.g., 2 hours at 120°C.

“Equilibrium swell” can be defined as the percent swell at equilibriumafter the hydratable cross-linked polymer material has been immersed ina wetting agent for a time period sufficient for water content to becomeconstant, typically 18 to 24 hours.

“Target site” is typically the location to which the sealant matrixcomposition is to be delivered, usually a tissue breach or defect.Often, the target site will be the tissue location of interest, but insome cases the sealant matrix composition may be administered ordispensed to a location near the location of interest, e.g., when thematerial swells in situ to cover the location of interest.

The hydratable cross-linked polymers for use as hydrogel-formingcomponents in at least some embodiments of the present invention may beformed from biologic and non-biologic polymers. Suitable biologicpolymers include proteins, such as gelatin, soluble collagen, albumin,hemoglobin, casein, fibrinogen, fibrin, fibronectin, elastin, keratin,laminin, and derivatives and combinations thereof. Soluble non-fibrillarcollagen is similarly suitable. Exemplary gelatin formulations are setforth below. Other suitable biologic polymers include polysaccharides,such as glycosaminoglycans (e.g., hyaluronic acid and chondroitinsulfate), starch derivatives, xylan, cellulose derivatives,hemicellulose derivatives, agarose, alginate, chitosan, and derivativesand combinations thereof. Suitable non-biologic polymers can be selectedto be degradable by either of two mechanisms, i.e. (1) break down of thepolymeric backbone or (2) degradation of side chains which result inaqueous solubility. Exemplary nonbiologic polymers include synthetics,such as polyacrylates, polymethacrylates, polyacrylamides, polyvinylresins, polylactide-glycolides, polycaprolactones, polyoxyethylenes, andderivatives and combinations thereof.

The hydratable cross-linked polymer molecules for use ashydrogel-forming components may be cross-linked in any manner suitableto form an aqueous hydrogel. For example, these polymeric molecules maybe cross-linked using bi- or poly-functional cross-linking agents whichcovalently attach to two or more polymer molecules chains. Exemplarybifunctional cross-linking agents include aldehydes, epoxies,succinimides, carbodiimides, maleimides, azides, carbonates,isocyanates, divinyl sulfone, alcohols, amines, imidates, anhydrides,halides, silanes, diazoacetate, aziridines, and the like. Alternatively,cross-linking may be achieved by using oxidizers and other agents, suchas periodates, which activate side-chains or moieties on the polymer sothat they may react with other side-chains or moieties to form thecross-linking bonds. An additional method of cross-linking comprisesexposing the polymers to radiation, such as gamma radiation, to activatethe side polymer to permit cross-linking reactions. Dehydrothermalcross-linking methods are also suitable. Dehydrothermal cross-linking ofgelatin can be achieved by holding it at an elevated temperature,typically 120° C., for a period of at least 8 hours. Increasing theextent of cross-linking, as manifested in a decline in percent swell atequilibrium, can be achieved by elevating the holding temperature,extending the duration of the holding time, or a combination of both.Operating under reduced pressure can accelerate the cross-linkingreaction. Preferred methods for cross-linking gelatin molecules aredescribed below.

Hydrogels may include a plasticizer to increase the malleability,flexibility, and rate of degradation of the hydrogel. The plasticizermay be an alcohol, such as polyethylene glycol, sorbitol, or glycerol.Often, the plasticizer will be polyethylene glycol having a molecularweight ranging from about 200 to 1000 D, or having a molecular weight ofabout 400 D. The plasticizers can be present in the hydrogel at fromabout 0.1% by weight to about 30% by weight, preferably from 1% byweight to 5% by weight of the polymer composition. The plasticizers canbe particularly beneficial for use with hydrogels having a high solidscontent, typically above 10% by weight of the composition (withoutplasticizer).

Exemplary methods for producing molecular cross-linked gelatins are asfollows. Gelatin is obtained and placed in an aqueous buffer to form anon-cross-linked gel, typically having a solids content from about 1% toabout 70% by weight, or from about 3% to about 10% by weight. Thegelatin is cross-linked, typically by exposure to either glutaraldehyde(e.g. 0.01% to 0.05% w/w, overnight at 0° C. to 15° C. in aqueousbuffer), sodium periodate (e.g. 0.05 M, held at 0° C. to 8° C. for 48hours) or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (“EDC”) (e.g.,0.5% to 1.5% w/w, overnight at room temperature), or by exposure toabout 0.3 to 3 megarads of gamma or electron beam radiation.Alternatively, gelatin particles can be suspended in an alcohol, such asmethyl alcohol or ethyl alcohol, at a solids content of about 1% toabout 70% by weight, or about 3% to about 10% by weight, andcross-linked by exposure to a cross-linking agent, typicallyglutaraldehyde (e.g., 0.01% to 0.1% w/w, overnight at room temperature).In the case of aldehydes, the pH is typically held from about 6 to about11, or from about 7 to about 10. When cross-linking with glutaraldehyde,the cross-links are formed via Schiff bases which may be stabilized bysubsequent reduction, e.g. by treatment with sodium borohydride. Aftercross-linking, the resulting granules may be washed in water andoptionally rinsed in an alcohol, dried and resuspended to a desireddegree of hydration in an aqueous medium having a desired buffer and pH.The resulting hydrogels may then be loaded into the applicators of thepresent invention, as described in more detail hereinafter.Alternatively, the hydrogels may be mechanically disrupted prior to orafter cross-linking, also as described in more detail hereinafter.

Exemplary methods for producing molecular cross-linked gelatincompositions having equilibrium percent swells in the range from about400% to about 1300%, or from about 600% to about 950%, are as follows.Gelatin is obtained and placed in an aqueous buffer (typically at a pHof about 6 to about 17, or at a pH between about 7 and about 10)containing a cross-linking agent in solution (often glutaraldehyde,typically at a concentration of 0.01% to 0.1% w/w) to form a gel,typically having a solids content from 1% to 70% by weight, usually from3% to 10% by weight. The gel is well mixed and held overnight at 0° to15° C. as cross-linking takes place. It is then rinsed three times withdeionized water, twice with an alcohol (preferably methyl alcohol, ethylalcohol, or isopropyl alcohol) and allowed to dry at room temperature.Optionally, the gel may be treated with sodium borohydride to furtherstabilize the cross-linking In some cases, the hydrogel-formingcomponent can include a gelatin having, for example, a large number ofglycine residues (e.g. 1 in 3 arranged every third residue), prolineresidues, and 4-hydroxyproline residues. An exemplary gelatin subunit isshown in FIG. 5. Gelatin embodiments include molecules having an aminoacid composition of: glycine 21%, proline 12%, hydroxyproline 12%,glutamic acid 10%, alanine 9%, arginine 8%, aspartic acid 6%, lysine 4%,serine 4%, leucine 3%, valine 2%, phenylalanine 2%, threonine 2%,isoleucine 1%, hydroxylysine 1%, methionine and histidine <1% andtyrosine <0.5%. FIG. 6 illustrates the correlation between percent swelland the percent solids of a fragmented crosslinked polymeric gelembodiment useful as a hydrogel-forming component in a sealantcomposition.

The molecular cross-linked hydrogels are preferably mechanicallydisrupted in a batch process prior for use as a hydrogel-formingcomponent. The primary purpose of this mechanical disruption step is tocreate multiple subunits of hydrogel having a size which enhances theability to fill and pack the space to which it is being delivered.Without mechanical disruption, the molecular cross-linked hydrogels willhave difficulty conforming to and filling the irregularly shaped targetspaces which are being treated. By breaking the hydrogel down to smallersized sub-units, such spaces can be filled much more efficiently whileretaining the mechanical integrity and persistence of the cross-linkedhydrogel.

Molecular cross-linking of the polymer chains of the hydrogel can beperformed before or after its mechanical disruption. The hydrogels maybe mechanically disrupted in batch operations, such as mixing, so longas the hydrogel composition is broken down into sub-units having a sizein the 0.01 mm to 5.0 mm range set forth above. Other batch mechanicaldisruption processes include pumping through a homogenizer or mixer orthrough a pump which compresses, stretches, or shears the hydrogel to alevel which exceeds a fractural yield stress of the hydrogel. In somecases, extrusion of the polymeric composition causes the hydrogel to beconverted from a substantially continuous network, i.e. a network whichspans the dimensions of the original hydrogel mass, to a collection ofsub-networks or sub-units having dimensions in the ranges set forthabove.

In a presently preferred embodiment, the hydratable cross-linked polymermay be initially prepared (e.g. by spray drying) and/or be mechanicallydisrupted prior to being cross-linked, often usually prior to hydrationto form a hydrogel. The hydratable cross-linked polymer may be providedas a finely divided or powdered dry solid which may be disrupted byfurther comminution to provide particles having a desired size, usuallybeing narrowly confined within a small range. Further size selection andmodification steps, such as sieving, cyclone classification, etc., mayalso be performed. For the exemplary gelatin materials describedhereinafter, the dry particle size is preferably in the range from about0.01 mm to about 1.5 mm, more preferably from about 0.05 mm to about 1.0mm. An exemplary particle size distribution will be such that greaterthan about 95% by weight of the particles are in the range from about0.05 mm to about 0.7 mm. Methods for comminuting the polymeric startingmaterial include homogenization, grinding, coacervation, milling, jetmilling, and the like. Powdered polymeric starting materials may also beformed by spray drying. The particle size distribution may be furthercontrolled and refined by conventional techniques such as sieving,aggregation, further grinding, and the like.

The dry powdered solid may then be suspended in an aqueous buffer, asdescribed elsewhere herein, and cross-linked. In other cases, thehydratable cross-linked polymer may be suspended in an aqueous buffer,cross-linked, and then dried. The cross-linked, dried polymer may thenbe disrupted, and the disrupted material subsequently resuspended in anaqueous buffer. In all the cases, the resulting material comprises across-linked hydrogel having discrete sub-networks having the dimensionsset forth above.

The hydratable cross-linked polymers useful as hydrogel-formingcomponents, after mechanical disruption, will typically be resorbable,i.e., they will biodegrade in the patient's body, in a period of lessthan one year, usually from 1 to 120 days, preferably from 1 to 90 days,and more preferably from 2 to 30 days following their initialapplication. Techniques for measuring the length of time required forresorption are known.

III. PREPARATION AND USE OF ONE GROUP OF EMBODIMENTS OF THE SEALANTMATRIX Compositions: Combination of Porous Matrix and HydratableCross-Linked Polymer

Compositions according to the present invention comprise a firstcross-linkable component combined with a second cross-linkable componentwhich are capable of cross-linking to form a porous matrix havinginterstices, which is combined with a hydratable cross-linked polymerthat is capable of being hydrated to form a hydrogel to fill at leastsome of the interstices. It will be appreciated that the compositions ofthe present invention can be used for a variety of biomedicalapplications, including each of the applications discussed above withreference to altering the (1) the first and second components (i.e.porous matrix); and, (2) the hydratable cross-linked polymer. Forexample, such compositions can act as a mechanical sealant to stop orinhibit bleeding by forming a rapid physical barrier to blood.Accordingly, some embodiments of the present invention can provideresults without a direct “hemostatic” effect (e.g., biochemical effecton clotting cascade; involving clotting initiators).

The hydrogel-forming component can serve as an absorbent (e.g. for bloodand other fluids and tissues). By absorbing blood, the hydrogel-formingcomponent can ensure that a higher concentration of the first and secondcross-linkable components is maintained at the treatment site, and canensure that a semi-dry surface is provided for the first and secondcross-linkable components to cross-link with each other and to thesurrounding tissues. In some embodiments, the first and secondcomponents can cross-link at the same time the hydrogel-formingcomponent is absorbing blood. This absorption and cross-linking canoccur within a matter of seconds, and the resulting sealant matrixbarrier can reach full strength at 30 minutes to one hour.

Generally, the sealant matrix compositions are “dry,” although someminimal moisture content may be present, e.g., in the hydrogel-formingcomponent. In some cases, it is possible to partially pre-hydrate thehydratable cross-linked polymer prior to application, although it may benecessary to do so at a higher pH than physiological pH, or under otherconditions which will prevent the first and second components fromcross-linking prior to application at the target site. Often, sealantmatrix compositions will be in a powdered or fused-cake form.

The concentrations of the first component and the second component usedto prepare the sealant matrix compositions may vary depending upon anumber of factors, including the types and molecular weights of theparticular cross-linkable components used and the desired end useapplication. In some embodiments, the weight ratio of the first andsecond components to the hydrogel-forming component ranges from 10-50%w/w, 15-45% w/w, 20-42% w/w, 30-40% w/w and 28 to about 42% w/w. In someembodiments, particle sizes for the first and second polymers can rangefrom about 50 to about 90 microns. In some embodiments, particle sizesfor the hydratable cross-linked polymer can range from about 250 toabout 400 microns.

In some embodiments, the first and second components may be provided asin dry particulate or powder form. In this form the first and secondcomponents may be mixed together, and further may be mixed with thehydrogel-forming component, also in dry particulate or powder form.Mixture of the components may be accomplished by any mechanicaladmixture means, such as milling blade mixing. The resulting dry powdersealant matrix composition may then be packaged in various containers,e.g., cartons, envelops, jars, and the like. Admixture and filling maybe done under aseptic conditions, or the sealant matrix composition maybe sterilized after packaging, e.g., by gamma radiation. The dry powderembodiments of the invention are then ready for use. The first andsecond cross-linkable polymers will react to cross-link underphysiological conditions (e.g., blood pH,) and so the three componentsealant matrix composition of the composition may be applied directly atthe desired site in dry form to seal a tissue defect, provided thatsufficient hydrating bodily fluid is present. Thus, the powdered sealantmatrix composition may simply be poured onto and into the tissue defecttarget site, and held in place (e.g., with a gauze pad or surgicalglove) until the sealant matrix barrier forms. This is particularlyuseful and convenient in trauma situations (e.g., in an emergency suiteor battlefield) where ready-to-use products that can be used withvarious tissue defect sizes are desirable.

In other embodiments, the first and second components and thehydrogel-forming component may be immobilized on a support, or backing,forming a “sealant matrix pad”. In these embodiments, a support, such asa collagen sponge, is provided, and then the sealant matrix compositionis fixed onto the support for use. Because the sealant matrixcompositions bond easily with tissues, organic materials, and syntheticmaterials, these embodiments can be advantageous in that a more easilyhandled support may be used to apply the sealant matrix composition. Dueto the fact that a relatively small amount of sealant matrix compositionis required to create an effective sealant matrix barrier, a relativelythin layer of sealant matrix composition may be fixed to the support.For instance, in the examples set forth below, only about 0.5-1.0 g ofsealant matrix composition fixed on the surface created a 3 cm×3 cm padwith very good haemostatic properties. As will be appreciated by thoseskilled in the surgical arts, these embodiments are desirable insituations where the size of the tissue defect is anticipated, and whenimproved handling characteristics as compared to a powder are desired.Like the dry powder embodiments, the sealant matrix pad embodiments ofthe sealant matrix compositions may be applied directly to the tissuedefect without further preparation by pressing the sealant matrixcomposition side of the pad against the tissue defect until thecross-linkable components have cross-linked.

The support for the sealant matrix pad embodiments of the invention maybe any biocompatible material. Although collagen supports are describedin detail herein, other materials for supports may be used. For example,other protein or polysaccharide support material which are biocompatiblemay be used. These support materials may degrade at approximately thesame rate in vivo as the sealant matrix barrier, or may degrade atdifferent rates from the sealant matrix barrier. Collagen sponges andtheir preparation are well known in the surgical arts, and thepreparation and handling of collagen is described fully below. Likewise,sponges prepared from fibrin may be used. Carbohydrate based materialssuch as cellulose (for external applications) or chitosan may also beused. In addition, biocompatible and biodegradable synthetic polymersmay be used. Those of skill in the surgical arts will recognize thatforms other than sponges may be used for supports in the sealant matrixpad embodiments of the invention. For example, a sheet or film ofcollagen or other materials may be used. In addition, the support maytake any useful shape, such as cones, hemispheres, rods, wedges, and thelike, in order to provide a pad that will more closely approximate theshape of the tissue defect. For example, a sealant matrix pad whichutilizes a cone-shaped collagen sponge as a support may be useful intreating a gunshot wound.

Typically, such supports will act as a structural or mechanicalcomponent. The supports may have some degree of porosity, to allow bloodor other liquids to seep into the support and have increased contactwith the compositions. Such constructions may have a swelling factor ofabout 1.3× to about 1.5×, and therefore can be ideal for surgicalapplications. For example, the sponge-supported compositions can be usedin neurosurgery to seal dura, where excessive swelling can placeunwanted pressure on the brain. In general, the supports should beflexible enough to conform to a typical tissue defect, and should havegood handling properties in the surgical context.

The sealant matrix compositions may be immobilized on the support by avariety of means. In some embodiments described below, gentle heat issufficient to immobilize powdered sealant matrix compositions containing4-arm PEG first and second components, and a cross-linked gelatinhydrogel-forming component. In these embodiments, the powdered sealantmatrix composition was placed onto a collagen sponge, and heated to60-70° C. for about 1-2 minutes. The dry powder matrix melted slightlyat this heat, fixing it to the surface of the collagen sponge.Alternatively, the sealant matrix composition may be fixed to thesupport using binding agents, or other excipients known in thepharmaceutical arts. In general, the technique used to fix the sealantmatrix composition to the support will depend on the first and secondcomponents and the hydrogel-forming component of the sealant matrixcomposition. The method used to fix the sealant matrix composition ontothe support should not appreciably decrease the ability of the first andsecond component to cross-link when exposed to physiological conditions,or the ability of the hydrogel-forming component to absorb biologicalfluids.

In other embodiments, the sealant matrix composition may be formed intoa sheet or film without a support. Such forming of the sealant matrixcomposition may be achieved using the methods described above for fixinga sealant matrix composition to a support for the sealant matrix padembodiments.

IV. ADDITION OF ADDITIONAL COMPONENTS IN THE SEALANT MATRIX COMPOSITION

In additional embodiments of the present invention, components otherthan the first and second cross-linkable components and thehydrogel-forming component may be added to the sealant matrixcompositions of the invention. In general, these additional componentsmay be admixed with the first and second and hydrogel-forming componentsin dry form. Additional components may add further mechanical strengthor otherwise improve the performance of the sealant matrix compositionsof the invention for particular applications. For instance, because itis opaque and less tacky than nonfibillar collagen, fibrillar collagenmay sometimes be less preferred for use in bioadhesive compositions.However, as disclosed in U.S. Pat. No. 5,614,587, fibrillar collagen, ormixtures of nonfibrillar and fibrillar collagen, may be preferred foruse in adhesive compositions intended for long-term persistence in vivo.Various deacetylated and/or desulfated glycosaminoglycan derivatives canbe incorporated into the composition in a similar manner as thatdescribed above for collagen.

Naturally occurring proteins, such as collagen, and derivatives ofvarious naturally occurring polysaccharides, such as glycosaminoglycans,can be incorporated into the sealant matrix barrier when the first andsecond components of the invention react under physiological conditionsto cross-link. When these other components also contain functionalgroups which will react with the functional groups on the syntheticpolymers, their presence during crosslinking of the first and secondcomponents at the target site will result in formation of a crosslinkedsynthetic polymer-naturally occurring polymer matrix. In particular,when the naturally occurring polymer (protein or polysaccharide) alsocontains nucleophilic groups such as primary amino groups, theelectrophilic groups on the second cross-linkable component will reactwith the primary amino groups on these components, as well as thenucleophilic groups on the first cross-linkable component, to causethese other components to become part of the sealant matrix barrier.

In general, glycosaminoglycans are typically chemically derivatized bydeacetylation, desulfation, or both in order to contain primary aminogroups available for reaction with electrophilic groups on the secondcross-linkable component. Glycosaminoglycans that can be derivatizedaccording to either or both of the aforementioned methods include thefollowing: hyaluronic acid, chondroitin sulfate A, chondroitin sulfate B(dermatan sulfate), chondroitin sulfate C, chitin (can be derivatized tochitosan), keratan sulfate, keratosulfate, and heparin. Derivatizationof glycosaminoglycans by deacetylation and/or desulfation and covalentbinding of the resulting glycosaminoglycan derivatives with synthetichydrophilic polymers is described in further detail in commonlyassigned, allowed U.S. Pat. No. 5,510,418, the contents of which arehereby incorporated by reference.

Similarly, electrophilic groups on the second cross-linkable componentmay react with primary amino groups on lysine residues or thiol groupson cysteine residues of certain naturally occurring proteins.Lysine-rich proteins such as collagen and its derivatives are especiallyreactive with electrophilic groups on synthetic polymers. As usedherein, the term “collagen” is intended to encompass collagen of anytype, from any source, including, but not limited to, collagen extractedfrom tissue or produced recombinantly, collagen analogues, collagenderivatives, modified collagens, and denatured collagens such asgelatin. Covalent binding of collagen to synthetic hydrophilic polymersis described in detail in commonly assigned U.S. Pat. No. 5,162,430,issued Nov. 10, 1992, to Rhee et al.

In general, collagen from any source may be used in the compositions ofthe invention; for example, collagen may be extracted and purified fromhuman or other mammalian source, such as bovine or porcine corium andhuman placenta, or may be recombinantly or otherwise produced. Thepreparation of purified, substantially non-antigenic collagen insolution from bovine skin is well known in the art. U.S. Pat. No.5,428,022, issued Jun. 27, 1995, to Palefsky et al., discloses methodsof extracting and purifying collagen from the human placenta. U.S. Pat.No. 5,667,839 discloses methods of producing recombinant human collagenin the milk of transgenic animals, including transgenic cows. The term“collagen” or “collagen material” as used herein refers to all forms ofcollagen, including those which have been processed or otherwisemodified.

Collagen of any type, including, but not limited to, types I, II, III,IV, or any combination thereof, may be used in the compositions of theinvention, although type I is often preferred. Either atelopeptide ortelopeptide-containing collagen may be used; however, when collagen froma xenogeneic source, such as bovine collagen, is used, atelopeptidecollagen is often preferred, because of its reduced immunogenicitycompared to telopeptide-containing collagen.

Collagen that has not been previously crosslinked by methods such asheat, irradiation, or chemical crosslinking agents can be used in thecompositions of the invention, and previously crosslinked collagen maybe used as well. Non-crosslinked atelopeptide fibrillar collagen iscommercially available from Collagen Corporation (Palo Alto, Calif.) atcollagen concentrations of 35 mg/ml and 65 mg/ml under the trademarksZyderm® I Collagen and Zyderm II Collagen, respectively. Glutaraldehydecrosslinked atelopeptide fibrillar collagen is commercially availablefrom Collagen Corporation at a collagen concentration of 35 mg/ml underthe trademark Zyplast® Collagen. Collagens for use in the presentinvention are generally in dry lyophilized powder form.

Because of its tacky consistency, nonfibrillar collagen is typicallyused in compositions of the invention that are intended for use asbioadhesives. The term “nonfibrillar collagen” encompasses any modifiedor unmodified collagen material that is in substantially nonfibrillarform at pH 7, as indicated by optical clarity of an aqueous suspensionof the collagen.

Collagen that is already in nonfibrillar form may be used in thecompositions of the invention. As used herein, the term “nonfibrillarcollagen” is intended to encompass collagen types that are nonfibrillarin native form, as well as collagens that have been chemically modifiedsuch that they are in nonfibrillar form at or around neutral pH.Collagen types that are nonfibrillar (or microfibrillar) in native forminclude types IV, VI, and VII.

Chemically modified collagens that are in nonfibrillar form at neutralpH include succinylated collagen and methylated collagen, both of whichcan be prepared according to the methods described in U.S. Pat. No.4,164,559, issued Aug. 14, 1979, to Miyata et al., which is herebyincorporated by reference in its entirety. Due to its inherenttackiness, methylated collagen is typically used in bioadhesivecompositions, as disclosed in U.S. Pat. No. 5,614,587.

Collagens for use in the sealant matrix compositions of the presentinvention may start out in fibrillar form, then be rendered nonfibrillarby the addition of one or more fiber disassembly agents. The fiberdisassembly agent is typically present in an amount sufficient to renderthe collagen substantially nonfibrillar at pH 7, as described above.Fiber disassembly agents for use in the present invention include,without limitation, various biocompatible alcohols, amino acids,inorganic salts, and carbohydrates, with biocompatible alcohols beingparticularly preferred. Preferred biocompatible alcohols includeglycerol and propylene glycol. In some cases, non-biocompatiblealcohols, such as ethanol, methanol, and isopropanol, may not bedesirable for use in the first and second polymers of the presentinvention, due to their potentially deleterious effects on the body ofthe patient receiving them. Examples of amino acids include arginine.Examples of inorganic salts include sodium chloride and potassiumchloride. Although carbohydrates, such as various sugars includingsucrose, may be used in the practice of the present invention, they arenot as preferred as other types of fiber disassembly agents because theycan have cytotoxic effects in vivo.

For use in tissue adhesion, in addition to sealing, it may also bedesirable to incorporate proteins such as albumin, fibrin or fibrinogeninto the sealant matrix composition to promote cellular adhesion. Inaddition, the introduction of hydrocolloids such ascarboxymethylcellulose may promote tissue adhesion and/or swellability.

The sealant matrix compositions of the present invention may alsocomprise one or more additional biologically active agents or compounds.In one embodiment, biologically active agents such as taxol derivativesmay be added to the sealant matrix composition to prevent adhesion atthe tissue defect site. In other embodiments, biologically active agentssuch as antibiotic or antimicrobial agents may be added to the sealantmatrix for use, e.g., in trauma-induced wound situations (e.g., knife orbullet wounds) where pathogenic organisms may have entered the tissuedefect site, or wound. In other embodiments, biologically active agentssuch as growth factors may be delivered from the composition to a localtissue site in order to facilitate tissue healing and regeneration. Infurther embodiments, blood clotting agents, such as thrombin, may beadded to further improve sealing and tissue regeneration by activatingthe clotting cascade. Exemplary bioactive components include, but arenot limited to, proteins, carbohydrates, nucleic acids, and inorganicand organic biologically active molecules such as enzymes, antibiotics,antineoplastic agents, bacteriostatic agents, anti-adhesion formationagents (such as taxol derivatives,) bacteriocidal agents, antiviralagents, hemostatic agents, local anesthetics, anti-inflammatory agents,hormones, antiangiogenic agents, antibodies, neurotransmitters,psychoactive drugs, drugs affecting reproductive organs andoligonucleotides, such as antisense oligonucleotides. The term“biologically active agent” or “active agent” as used herein encompassesorganic or inorganic molecules which exert biological effects in vivo.Examples of active agents include, without limitation, enzymes, receptorantagonists or agonists, hormones, growth factors, autogenous bonemarrow, antibiotics, anti-adhesion formation agents, antimicrobialagents, other pharmaceutical agents, and antibodies. The term “activeagent” is also intended to encompass combinations or mixtures of two ormore active agents, as defined above.

Such bioactive components will typically be present at relatively lowconcentrations, typically below 10% by weight of the compositions,usually below 5% by weight, and often below 1% by weight. Two or more ofsuch active agents may be combined in a single composition and/or two ormore compositions may be used to deliver different active componentswhere said components may interact at the delivery site. Exemplaryhemostatic agents include thrombin, fibrinogen and clotting factors.Hemostatic agents like thrombin may be added in concentrations ranging,for example, from about 50 to about 10,000 Units thrombin per mlhydrogel, or from about 100 to about 1000 Units thrombin per mlhydrogel.

The crosslinked first and second polymer compositions can also beprepared to contain various imaging agents such as iodine or bariumsulfate, or fluorine, in order to aid visualization of the compositionsafter administration via X-ray, or ¹⁹F-MRI, respectively.

Preferred active agents for use in the compositions of the presentinvention include growth factors, such as transforming growth factors(TGFs), fibroblast growth factors (FGFs), platelet derived growthfactors (PDGFs), epidermal growth factors (EGFs), connective tissueactivated peptides (CTAPs), osteogenic factors, and biologically activeanalogs, fragments, and derivatives of such growth factors. Members ofthe transforming growth factor (TGF) supergene family, which aremultifunctional regulatory proteins, are particularly preferred. Membersof the TGF supergene family include the beta transforming growth factors(for example, TGF-β1, TGF-β2, TGF-β3); bone morphogenetic proteins (forexample, BMP-1, BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7, BMP-8, BMP-9);heparin-binding growth factors (for example, fibroblast growth factor(FGF), epidermal growth factor (EGF), platelet-derived growth factor(PDGF), insulin-like growth factor (IGF)); Inhibins (for example,Inhibin A, Inhibin B); growth differentiating factors (for example,GDF-1); and Activins (for example, Activin A, Activin B, Activin AB).

Growth factors can be isolated from native or natural sources, such asfrom mammalian cells, or can be prepared synthetically, such as byrecombinant DNA techniques or by various chemical processes. Inaddition, analogs, fragments, or derivatives of these factors can beused, provided that they exhibit at least some of the biologicalactivity of the native molecule. For example, analogs can be prepared byexpression of genes altered by site-specific mutagenesis or othergenetic engineering techniques.

Biologically active agents may be incorporated into the sealant matrixcomposition by admixture. In one embodiment, active agents may be mixedinto powdered sealant matrix compositions in a dry or lyophilized form.In another embodiment, this admixture may be fixed onto a solid supportsuch as collagen as described above for the sealant matrix compositions.In other embodiments, the agents may be incorporated into the sealantmatrix compositions, as described above, by binding these agents withthe functional groups on the first or second component syntheticpolymers. Processes for covalently binding biologically active agentssuch as growth factors using functionally activated polyethylene glycolsare described in commonly assigned U.S. Pat. No. 5,162,430, issued Nov.10, 1992, to Rhee et al. Such compositions preferably include linkagesthat can be easily biodegraded, for example as a result of enzymaticdegradation, resulting in the release of the active agent into thetarget tissue, where it will exert its desired therapeutic effect.

A simple method for incorporating biologically active agents containingnucleophilic groups into the crosslinked polymer composition involvesmixing the active agent with the first component, second component, andhydrogel forming component prior to administration in a dry state. Uponapplication of the sealant matrix composition to the tissue defect andcontact with biological fluid, the biologically active agent will reactwith the second component and be cross-linked into the porouscross-linked matrix of the first and second components, as thehydrogel-forming component absorbs the biological fluid. This procedurewill result in covalent binding of the active agent to the crosslinkedcomponent polymer matrix portion of the sealant matrix barrier which isformed, producing a highly effective sustained release composition.

The type and amount of active agent used will depend, among otherfactors, on the particular site and condition to be treated and thebiological activity and pharmacokinetics of the active agent selected.

V. USE OF SEALANT MATRIX COMPOSITIONS AS BIOADHESIVES

The sealant matrix compositions of the present invention are generallyadhesive and bond to tissues strongly, as the electrophilic groups ofthe second cross-linkable component react with nucleophilic groups ofcollagen in the tissue of the target site. Some porous matrixcompositions of the invention can have unusually high tackiness. Thus,in addition to use as a barrier matrix for hemostasis, the sealantmatrix compositions of the present invention are useful as bioadhesivesto bond wet or moist tissues under physiological conditions. As usedherein, the terms “bioadhesive”, “biological adhesive”, and “surgicaladhesive” may be used interchangeably to encompass biocompatiblecompositions capable of effecting temporary or permanent attachmentbetween the surfaces of two native tissues, or between a native tissuesurface and a non-native tissue surface or a surface of a syntheticimplant.

In a general method for effecting the attachment of a first surface to asecond surface, the sealant matrix composition (for example, in drypowder or sheet form) is applied to a first surface. The first surfaceis then contacted with the second surface, preferably immediately, toeffect adhesion between the two surfaces. At least one of the first andsecond surfaces is preferably a native tissue surface. When amechanically stable hydrogel forming component is used in thecomposition, such as the crosslinked gelatin used in the examples, theresulting porous matrix exhibits increased mechanical strength asopposed to a composition containing the first and second cross-linkablecomponents alone. Thus, the strength of the adhesion between the twotissue surfaces is also increased, as the layer of porous matrix betweenthe tissues will be less likely to separate internally underphysiological mechanical stresses.

The two surfaces may be held together manually, or using otherappropriate means, while the crosslinking reaction is proceeding tocompletion. Crosslinking is typically complete within 5 to 60 minutesafter applying the sealant matrix composition. However, the timerequired for complete crosslinking to occur is dependent on a number offactors, including the types and molecular weights of the first andsecond cross-linkable components and, most particularly, the effectiveconcentrations of the two components at the target site (i.e., higherconcentrations result in faster crosslinking times).

At least one of the first and second surfaces is preferably a nativetissue surface. As used herein, the term “native tissue” encompassesbiological tissues that are native to the body of the specific patientbeing treated. As used herein, the term “native tissue” encompassesbiological tissues that have been elevated or removed from one part ofthe body of a patient for implantation to another part of the body ofthe same patient (such as bone autografts, skin flap autografts, etc.).For example, the compositions of some embodiments of the invention canbe used to adhere a piece of skin from one part of a patient's body toanother part of the body, as in the case of a burn victim.

The other surface may be a native tissue surface, a non-native tissuesurface, or a surface of a synthetic implant. As used herein, the term“non-native tissue” encompasses biological tissues that have beenremoved from the body of a donor patient (who may be of the same speciesor of a different species than the recipient patient) for implantationinto the body of a recipient patient (e.g., tissue and organtransplants). For example, the crosslinked polymer compositions of thepresent invention can be used to fix a xenograft heart valve into theheart of a patient and seal around the heart valve to prevent leakage.

As used herein, the term “synthetic implant” encompasses anybiocompatible material intended for implantation into the body of apatient not encompassed by the above definitions for native tissue andnon-native tissue. Synthetic implants include, for example, artificialblood vessels, heart valves, artificial organs, bone prostheses,implantable lenticules, vascular grafts, stents, and stent/graftcombinations, etc.

VI. USE OF THE SEALANT MATRIX COMPOSITIONS TO PREVENT ADHESIONS

Another use of the sealant compositions of the invention is to coattissues in order to prevent the formation of adhesions following surgeryor injury to internal tissues or organs. In a general method for coatingtissues to prevent the formation of adhesions following surgery, thefirst and second synthetic polymers are mixed with the hydratablecrosslinked polymer or premixed, then a thin layer of the reactionmixture is applied to the tissues comprising, surrounding, and/oradjacent to the surgical site before substantial crosslinking hasoccurred between the nucleophilic groups on the first synthetic polymerand the electrophilic groups on the second synthetic polymer.Application of the reaction mixture to the tissue site may be byextrusion, sprinkling, brushing, spraying (as described above) forpowdered compositions, by placement of a thin film or sheet of thesealant matrix composition onto the tissue, or by any other convenientmeans.

Following application of the reaction mixture to the surgical site,crosslinking is allowed to continue in situ prior to closure of thesurgical incision. Once crosslinking has reached equilibrium, tissueswhich are brought into contact with the coated tissues will not stick tothe coated tissues. At this point in time, the surgical site can beclosed using conventional means (sutures, etc.).

In general, compositions that achieve complete crosslinking within arelatively short period of time (i.e., 5-15 minutes following mixture ofthe first synthetic polymer and the second synthetic polymer) may bepreferred for use in the prevention of surgical adhesions, so that thesurgical site may be closed relatively soon after completion of thesurgical procedure. Furthermore, it is preferred that a hydratablecrosslinked polymer with a relatively high mechanical strength be usedin the compositions, such as the crosslinked gelatin used in theexamples, to increase the mechanical stability of the coating.

The following examples describe the production and characterization of afirst cross-linkable component with a second cross-linkable componentand a hydrogel-forming component to form sealant matrix compositions,and are put forth so as to provide those of ordinary skill in the artwith a complete disclosure and description of how to make the preferredembodiments of the conjugates, compositions, and devices and are notintended to limit the scope of what the inventors regard as theirinvention. Efforts have been made to ensure accuracy with respect tonumbers used (e.g., amounts, temperature, molecular weight, etc.) butsome experimental errors and deviation should be accounted for. Unlessindicated otherwise, parts are parts by weight, molecular weight isweight average molecular weight, temperature is in degrees Centigrade,and pressure is at or near atmospheric.

VII. EXAMPLES Example 1 First and Second Component Compositions for Usein Sealant Matrix: Preparation of Crosslinked Multi-Amino PEGCompositions

The following stock solutions of various di-amino PEGs were prepared:Ten (10) grams of Jeffamine ED-2001 (obtained from Texaco ChemicalCompany, Houston, Tex.) was dissolved in 9 ml of water. Ten (10) gramsof Jeffamine ED-4000 (also obtained from Texaco Chemical Company) wasdissolved in 9 ml of water. 0.1 grams of di-amino PEG (3400 MW, obtainedfrom Shearwater Polymers, Huntsville, Ala.) was dissolved in 300 μl ofwater. Each of the three di-amino PEG solutions prepared above was mixedwith aqueous solutions of trifunctionally activated SC-PEG (TSC-PEG,5000 MW, also obtained from Shearwater Polymers) as set forth in Table1, below.

TABLE 1 Preparation of Crosslinked Polymer Compositions Di-amino PEGTSC-PEG + Aqueous Solvent 50 μl  0 mg + 50 μl water 50 μl 10 mg + 50 μlPBS 50 μl 10 mg + 100 μl PBS 250 μl  50 mg + 500 μl PBS

The solutions of di-amino PEG and TSC-PEG were mixed usingsyringe-to-syringe mixing. Each of the materials was extruded from thesyringe and allowed to set for 1 hour at 37° C. Each of the materialsformed a gel. In general, the gels became softer with increasing watercontent; the gels containing the least amount of aqueous solvent (wateror PBS) were firmest.

Example 2 First and Second Component Compositions for Use in SealantMatrix: Preparation of Crosslinked Poly(Lysine) Compositions

Ten (10) milligrams of poly-L-lysine hydrobromide (8,000 MW, obtainedfrom Peninsula Laboratories, Belmont, Calif.) in 0.1 ml phosphate buffer(0.2M, pH=6.6) was mixed with 10 mg of tetrafunctionally activatedSE-PEG (10,000 MW, obtained from Shearwater Polymers, Huntsville, Ala.)in 0.1 ml PBS. The composition formed a soft gel almost immediately.

Example 3 First and Second Component Compositions for Use in SealantMatrix: Effect of pH on Gel Formation of Tetra-Amino PEG/Tetra SE-PEGFormulations

Gels comprising various concentrations of tetra-amino PEG and tetraSE-PEG at pH 6, 7, and 8 were prepared in petri dishes. Following mixingof the tetra-amino PEG and tetra SE-PEG, the dishes were tiltedrepeatedly; the gelation time was considered to be the point at whichthe formulation ceased to flow. The effect of pH on gelation time of thevarious tetra-amino PEG/tetra SE-PEG formulations at room temperature isshown in Table 2, below.

TABLE 2 Effect of pH on Gel Formation of Tetra-amino PEG/Tetra SE-PEGFormulations Tetra-amino PEG Tetra SE-PEG Conc. (mg/ml) Conc. (mg/ml) pHGelation Time 20 20 6 >90.0 min 20 20 7 20.0 min 20 20 8 1.4 min 50 50 624.0 min 50 50 7 3.5 min 50 50 8 10.0 sec 100 100 6 9.0 min 100 100 747.0 sec 100 100 8 10.0 sec 200 200 6 2.0 min 200 200 7 9.0 sec 200 2008 5.0 sec

The time required for gel formation decreased with increasing pH andincreasing tetra-amino PEG and tetra SE-PEG concentrations.

Example 4 Evaluation of Hydrogel-Forming Component Materials and Methodsof Cross-Linking and Measuring Percent Swell

Gelatin particles were allowed to swell in an aqueous buffer (e.g., 0.2M sodium phosphate, pH 9.2) containing a cross-linking agent (e.g.,0.005 to 0.5% by weight glutaraldehyde). The reaction mixture was heldrefrigerated overnight and then rinsed three times with deionized water,twice with ethyl alcohol, and allowed to dry at ambient temperature. Thedried, cross-linked gelatin was resuspended in an aqueous buffer at alow solids concentration (2-3%) at ambient temperature for a fixedperiod of time. Buffer was in substantial excess of the concentrationneeded for equilibrium swelling, and two phases (a hydrogel phase and abuffer) were present. The suspension containing wet hydrogel was thenfiltered by applying vacuum on a 0.8 μm nominal cut-off filter membrane(Millipore, Bedford, Mass.). After removal of extraneous buffer, thecombined weight of the retained wet hydrogel and wet filter membrane wasrecorded. The hydrogel and membrane were then dried at approximately120° C. for at least two hours, and the combined weight of the driedhydrogel residue and dried filter membrane was recorded. Severalmeasurements of samples of wet filter membrane without hydrogel residueand dried filter membrane without hydrogel were also performed and wereused to deduce the net weight of wet hydrogel and dry hydrogel. “Percentswell” was then calculated as follows:

percent swell=100×[(wet weight of hydrogel−dry weight of hydrogel)/dryweight of hydrogel]

Swell measurements were conducted at least in triplicate and averagedfor a given sample of gelatin. The value of percent swell for samplesresuspended in buffer for 18 to 24 hr prior to measuring wet weight wasdefined as “equilibrium swell.”

The resulting cross-linked gelatin materials displayed equilibrium swellvalues in the range from 400% to 1300%. The degree of equilibrium swelldepended on the method and extent of cross-linking

Example 5 Hydrogel-Forming Components for Use in the Sealant Matrix:Fragmented Hydratable Cross-Linked Polymeric Product Composed of GelatinCross-Linked Using EDC

Gelatin (Atlantic Gelatin, General Foods Corp., Woburn, Mass.) wasallowed to dissolve in distilled water at 1 to 10% solids (w/w) (morepreferably at 8%) at 70° C. 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) (Sigma, St. Louis, Mo.) at 0.2% to 3.5% (or 0.2% to0.3%) was then added. The resultant hydrogel formed on stirring was leftat room temperature for one hour. The hydrogel was dried using aFreezone 12 freeze dry system, (Labconco, Mo.) and ground finely using aWaring Blender model No. 31BC91 (VWR, Willard, Ohio). The driedpolymeric composition was then loaded into syringes and equilibratedwith buffer. The equilibrium swell was determined to be at least 1000%.The results are shown in Table 3.

TABLE 3 Gelatin (mg) EDC Swell (%) 500 (8%) 13.5 mg (0.25%) 1080 500(8%) 13.5 mg (0.25%) 1126 100 (7.4%) 0.945 mg (0.35%)  1620 100 (7.4%)9.45 mg (3.5%)  1777

Example 6 Hydrogel-Forming Components for Use in the Sealant Matrix:Fragmented Hydratable Cross-Linked Polymeric Product Composed of Gelatinand Poly(L)Glutamic Acid, Cross-Linked Using EDC

Gelatin (Atlantic Gelatin, General Foods Corp., Woburn, Mass.) wasallowed to dissolve in distilled water at 1 to 10% solids (w/w) (morepreferably at 6 to 8%) at 70° C., 0 to 10% (w/w) (more preferably 2-5%)Poly(L)glutamic acid (PLGA) (Sigma, St. Louis, Mo.) and1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) (Sigma) at 0.2 to3.5% (or 0.2 to 0.4%) were then added. The resultant hydrogel formed onstirring was left at room temperature for one hour. The hydrogel wasallowed to swell in excess saline for a fixed period of time (forexample 20 hr). The hydrogel was then filtered by applying vacuum on afilter membrane (Millipore, Bedford, Mass.). The equilibrium swell wasdetermined to be at least 1500%. The results are shown in Table 4.

TABLE 4 Gelatin (mg) PLGA (mg) EDC Swell (%) 375 (6%)   125 (2%)   13.5mg (.25%) 1510 375 (6%)   125 (2%)   13.5 mg (.25%) 1596 250 (4%)   250(4%)   13.5 mg (.25%) 2535 250 (4%)   250 (4%)   13.5 mg (.25%) 2591 250(4%)   250 (4%)   13.5 mg (.25%) 2548 250 (4%)   250 (4%)   13.5 mg(.25%) 2526 200 (3.2%) 300 (4.8%) 13.5 mg (.25%) 2747 200 (3.2%) 300(4.8%) 13.5 mg (.25%) 2677 200 (3.2%) 300 (4.8%) 13.5 mg (.25%) 2669 150(2.4%) 350 (5.6%) 13.5 mg (.25%) 3258 150 (2.4%) 350 (5.6%) 13.5 mg(.25%) 3434 150 (2.4%) 350 (5.6%) 13.5 mg (.25%) 3275  75 (5.5%)  25(1.9%) 0.945 mg (0.35%) 2437  50 (3.7%)  50 (3.7%) 0.945 mg (0.35%) 2616 25 (1.9%)  75 (5.5%) 0.945 mg (0.35%) 5383  75 (5.5%)  25 (1.9%) 9.45mg (3.5%) 1976  50 (3.7%)  50 (3.7%) 9.45 mg (3.5%) 2925  25 (1.9%)  75(5.5%) 9.45 mg (3.5%) 4798

Example 7 Hydrogel-Forming Components for Use in the Sealant Matrix:Production of a Fragmented Hydratable Cross-Linked Polymeric Hydrogel

Bovine Corium (Spears Co. PA) was agitated in an aqueous sodiumhydroxide (Spectrum Chemical Co., CA) solution (0.1 M to 1.5 M, or 0.4to 1.2M) for a period of one to 18 hours (or one to four hours) at atemperature of 2° C. to 30° C. (preferably 22° C. to 30° C.). The coriumslurry was then neutralized using an inorganic acid such as hydrochloricacid, phosphoric acid or sulfuric acid (Spectrum Chemical Co., CA.) andthe neutralized liquid phase was then separated from the insolublecorium by filtration through a sieve. The corium was then washed withnon-pyrogenic water and an alcohol such as isopropyl alcohol (SpectrumChemical Co., CA.). After three to twelve washes, the corium wassuspended in non-pyrogenic water and the corium, water slurry may bethen heated to 50° C. to 90° C. preferably 60° C. to 80° C. to thermallygelatinize the corium. During the gelatinization cycle, the pH of thecorium, water slurry was adjusted and controlled from pH 3 to pH 11, orpH 7 to pH 9. Also, the insoluble corium in the slurry may be disruptedby agitation and/or homogenization. The disruption can occur before orafter the thermal gelatinization cycle. Thermal gelatinization wasconducted for one to six hours. After gelatinization, the slurry wasclarified by filtration. The gelatin slurry was dewatered by drying inair at 15° C. to 40° C., preferably 20° C. to 35° C. The dry gelatin,where dry implies a moisture content less than 20% by weight, was thendisrupted by grinding.

Dry gelatin was added to a cold (5° C. to 15° C.) aqueous solution ofcontaining glutaraldehyde (Amresco Inc., OH.) at 0.0025% to 0.075% byweight and at a pH between 7 and 10. The concentration of gelatin inthis solution was between 1% and 10% by weight. The glutaraldehydecross-links the gelatin granules over a period of one to 18 hours afterwhich the gelatin was separated from the aqueous phase by filtration orsedimentation. The gelatin particles were then added to an aqueoussolution containing 0.00833% to 0.0667% by weight sodium borohydride(Spectrum Chemical Co., CA.) with the gelatin concentration again beingbetween 1% and 10% by weight and the pH being between 7 and 12, orbetween 7 to 9. After one to six hours, the cross-linked gelatin wasseparated from the aqueous phase by filtration or sedimentation. Thegelatin may then be resuspended in non-pyrogenic water with the gelatinconcentration being between 1% and 10% by weight to remove residualcross-linking and reducing agents followed by separation from theaqueous phase by filtration or sedimentation. Final collection of thecross-linked gelatin was done on a filter mesh or sieve and the gelatinwas given a final rinse with non-pyrogenic water. The wet, cross-linkedgelatin was then placed in a drying chamber at 15° C. to 40° C. Dry,cross-linked gelatin (i.e. cross-linked gelatin with a moisture contentbelow 20% by weight) was removed from the drying chamber and then groundusing a mechanical, grinding mill to produce a powder with a typicalparticle size distribution from 0.020 mm to 2.000 mm.

Example 8 Rapidly Acting Dry Hemostatic Sealant Powder

A rapidly acting dry hemostatic sealant powder was prepared by combininga first cross-linkable component, a second cross-linkable components,and a hydrogel-forming component. The first cross-linkable polymer(PEG-A) was a PEG-succinimidyl powder, the second cross-linkable polymer(PEG-B) was a PEG-thiol powder, and the hydrogel-forming component was across-linked gelatin powder.

Example 9 Rapidly Acting Dry Sealant Pad

A rapidly acting dry sealant pad was prepared by combining a firstcross-linkable component, a second cross-linkable components, and ahydrogel-forming component. The resulting composition, a powderedsealant matrix composition, was placed onto a lyophilized collagensponge, and heated to 60-70° C. for about 1-2 minutes. The dry powdermatrix melted slightly at this heat, fixing it to the surface of thecollagen sponge, thus forming a sealant matrix pad. Alternatively, thesealant matrix composition may be fixed to the support using bindingagents, or other excipients known in the pharmaceutical arts. Ingeneral, the technique used to fix the sealant matrix composition to thesupport may depend on the first and second components and thehydrogel-forming component of the sealant matrix composition. Sealantmatrix pad embodiments of the present invention provide a convenientformat by which sealant matrix compositions may be handled and deliveredto a surgical site via a sponge or other suitable support means.

Example 10 Sealant Powder to Treat Splenic Artery Puncture

FIGS. 7A-E illustrate the application of a sealant matrix composition totreat a splenic artery puncture according to embodiments of the presentinvention. The pig was heparinized to approximately 3× baseline. Asdepicted in FIG. 7A, a splenic artery puncture was surgically induced ina pig with an 18 g needle 700. Following the puncture, excessivebleeding 705 was observed from the artery 710. As shown in FIGS. 7B and7C, approximately 700 mg of a sealant powder matrix composition 720 wasapplied to the puncture site via a syringe 730, and gently compressed orplaced against the site for two minutes using a gloved finger 740. Thesealant powder formed a coagulum 750 that was observed to adequatelystop the bleeding. The site was irrigated at 5 minutes post-applicationwith an irrigation device 760, as illustrated in FIG. 7D, and excesspowder composition was washed away. When the coagulum was grasped withforceps, it appeared to adhere quite well to the tissue and had goodintegrity. As shown in FIG. 7E, the coagulum 750 was removed at 44minutes post-application, by peeling off with forceps 770, and resumedbleeding 715 was observed.

Example 11 Sealant Powder to Treat Hepatic Resection

FIGS. 8A-E illustrate the application of a sealant matrix composition totreat a hepatic resection according to embodiments of the presentinvention. A pig was heparinized to approximately 3× baseline. As shownin FIG. 8A, the tip 800, or edge, of the middle lobe of the liver 805was resected in the pig using scissors 810. Following the resection,excessive bleeding 815 was observed from the site. As depicted in FIG.8B, approximately 6 ml (2 g) of a sealant matrix composition 820 wasapplied to the site, and held in place with the tip of a syringe 825 for2 minutes. As shown in FIG. 8C, a gloved finger can be used to compressor hold the powder against the lesion. The sealant powder formed acoagulum 835 that was observed to adequately stop the bleeding. The sitewas irrigated at 8 minutes post-application with an irrigation device840, as illustrated in FIG. 8D. When the coagulum was grasped withforceps, it appeared to adhere quite well to the tissue and had goodintegrity. The coagulum 835 was removed at 28 minutes post-application,by peeling off with forceps 845, and resumed bleeding 850 was observed.

Example 12 Sealant Powder to Treat Splenic Lesion

A splenic lesion was surgically induced in a pig with a 6 mm biopsytissue punch, and the tissue core was removed with scissors. The pig washeparinized to approximately 2.5× baseline. Following the tissue punch,excessive bleeding was observed from the spleen. Approximately 700 mg (2ml) of a sealant matrix composition powder was applied to the punctureusing the edge of a 12 ml syringe. No compression was used to hold thematerial in place. The sealant powder formed a coagulum that wasobserved to adequately stop the bleeding. The site was irrigated at 4minutes post-application. When the coagulum was grasped with forceps, itappeared to adhere quite well to the tissue and had good integrity. Thecoagulum was removed at 25 minutes post-application, by peeling off, andresumed bleeding was observed.

Example 13 Mechanical Stress Test

Sealant matrix barrier was prepared by reacting 0.60 to 0.65 g of asealant matrix composition powder with 1 ml porcine plasma in a plasticmold. The mixture was allowed to cure at room temperature forapproximately 30 minutes. Both ends of a 3×1×0.3 cm block of gel weretaped with cyanoacrylate glue to create gripping spaces for pullingapart (1×1 cm). The tape ends were gripped with the pre-mounted grips. AChatillon TCD2000 tester was used to apply a normal stress test to therectangular gel shape until fracture, to determine the tensile strength.Peak force (N) and deflection at maximum load (mm) were measured toextend the gel until break. The effective surface area of the gel was1×0.3 cm, and the original effective length of the gel was 1 cm. Thetensile strength of the sealant gel was approximately 15.3 N/cm². Asimilar test was performed on a gel composition including a firstcross-linkable component and a second cross-linkable component, in theabsence of a hydrogel-forming component, and the observed tensilestrength was approximately 5.1 N/cm².

Example 14 Peel Strength Test

In some embodiments, a mixed powder includes first and secondcross-linkable components and a hydrogel-forming component, and isself-polymerizing as it dissolves in a physiological liquid such asblood or another body fluid. The material can tightly adhere to a tissueor another application site by covalent bonding. The mechanical strengthof tissue adherence can be examined using a mechanical jig to pull asealant matrix from a tissue such as skin. In this example, multipletensile tests were run following formation of sealant matrix barriers asfollows. A series of three component powders containing a firstcross-linkable component (pentaerythritol poly (ethylene glycol) ethertetra-succinimidyl glutarate) and a second cross-linkable component(pentaerythritol poly (ethylene glycol) ether tetra-thiol), and across-linked gelatin (FloSeal™) were prepared, by mixing thecross-linkable components and the cross-linked gelatin at threedifferent concentrations (10%, 20%, and 30% of the cross-linkablecomponent). About 0.40 g to about 0.45 g of the three component powderwas added to about 0.6 ml of porcine plasma in a 3×1×0.3 cm plastic molddisposed on top of a chicken skin sample, and allowed to cure at roomtemperature for approximately 60 minutes. A sealant matrix barrierformed and tightly adhered to the skin. The formed sealant matrixbarrier was glued to a plate that was clamped to a Chatillon TCD200tester. Maximum peak force (N) was measured as skin was pulled from thesealant matrix barrier. An increase in adhering strength was observed toalmost linearly correlate with an increase in concentration of the PEGmixture (first and second cross-linkable components). Results are asshown in Table 4A.

TABLE 4A Conc. of PEG Speed, Curing Time, Pulling mixture Skin mm/minmin side, cm Force N 10% chicken 12.7 80 1 2.00 10% chicken 12.7 80 12.10 10% chicken 12.7 80 1 1.70 1.93 Avg. 0.21 Std. Dev. 20% chicken12.7 60 1 3.24 20% chicken 12.7 60 1 2.13 20% chicken 12.7 60 1 3.41 20%chicken 12.7 70 1 2.10 2.72 Avg. 0.71 Std. Dev. 30% chicken 12.7 70 13.86 30% chicken 12.7 70 1 7.86 30% chicken 12.7 80 1 1.53 30% chicken12.7 80 1 2.65 30% chicken 12.7 80 1 2.59 30% chicken 12.7 80 1 3.83 30%chicken 12.7 105 1 3.32 30% chicken 12.7 107 1 3.00 3.58 Avg. 1.89 Std.Dev.

Example 15 Preparation of Fibrillar Collagen for Sponge Backing of FusedPad

A first fibrillar collagen sample was prepared as follows. 40 g of NaOHwas dissolved in 450 cc H₂O at a temperature of 25° C. Approximately 50g of sliced bovine corium was added to the NaOH solution. The corium wasstirred for 80 minutes. The NAOH solution was decanted and the coriumwas washed with H₂O. The corium was dissolved with 2M HCl to bring thepH in the range of 2.3 to 2.4. Stirring was continued for 18 hours. 1250ml of thick collagen in solution (CIS) was titrated to pH 7.25 with 1MNaOH at 18° C. Collagen fiber was formed over a period of 10 hours, andfiltered. 240 ml of was precipitated at pH 7.4, and cross-linked with 33μA of 25% glutaraldehyde (GA) solution at 8° C. for 23 hours. Fibrillarcollagen was lyophilized using a Virtis Lyophilizer by a recipe cycle.

A second fibrillar collagen sample was prepared as follows. Fibrillarcollagen was cross-linked using 240 g of viscous solution (e.g. CIS).The solution was diluted by adding 60 cc of H₂O. The pH was raised to9.2 by adding about 1.8 cc of 2M NaOH. The temperature of the solutionwas adjusted to 8° C., and 33 μA of 25% GA was added. The solution wasstirred for 23 hours, and about 54 g of precipitated fibers wereobtained. Fibrillar collagen was lyophilized using a Virtis Lyophilizerby a recipe cycle.

Example 16 De-Buffering the Hydrogel-Forming Component

In some embodiments, it may be desirable to remove phosphate salt from ahydrogel-forming component such as FloSeal™ so that the pH of thehydrogel-forming component can be easily influenced by the surroundingliquid. In-situ cross-linking of hydrogel-forming components can help asealant matrix compound adhere to tissue following application. In somecases, the adhesion may be more effective at certain pH values. Forexample, some gelatin-based materials may undergo adhesion more readilyat pH values lower than 6 or 7. FloSeal™ was washed with H₂O in a ratioof 1:50, and the slurry was pH adjusted or acidified with 0.01M HCl or0.01M NaOH to a pH between 2 and 7. Wet gelatin cake was filtered anddried in a forced air oven at 32° C. for 12 to 20 hours and lightlyground with mortar and pestle. Dried gelatin powder was added to asolution of mixed PEG for in situ cross-linking A slurry was mixed for30 seconds and immediately applied to the surface of weighing paperfully saturated with 25 mM of phosphate buffer at pH 7.4. Polymerizationtimes were recorded, and the results are shown in Table 5.

TABLE 5 Time (minutes) Sample pH of FloSeal ™ pH of buffer for PEG (A/B)gelation 1 7.6 6 3 2 7.6 6 5 3 6.0 6 30 4 6.5 6 20 5 4.0 6 90

Example 17 Preparation of PEG Cake

In one embodiment, 0.8 g PEG-succinimide powder and 0.8 g PEG-thiolpowder were thoroughly mixed by shaking, and placed in a 100 ml roundbottom flask which was fully charged with N₂. The mixed powder wasmelted in a 40° C.-50° C. oil bath with gentle manual stirring for 30minutes, and allowed to cool. A solid film was removed from the flaskusing a spatula. In another embodiment, a mixed powder ofPEG-succinimide and PEG-thiol was dissolved in an acidic solution ofcollagen (e.g. 0.3%) or gelatin (e.g. 2%), and lyophilized. It isthought that the fibrillar collagen or gelatin may help to loosen thematrix and improve handling of the PEG cake.

In a comparative composition, 1.2 g of collagen fiber was dissolved in100 cc of pH 2 HCl, warmed in a 35° C. water bath for 1 to 2 hours, anddiluted with pH 2 HCl to achieve a 0.3% CIS product. 0.2 gPEG-succinimide and 0.2 g PEG-thiol were dissolved in 2 cc of the 0.3%CIS. The resulting mixture was poured into a tray, and lyophilizedthrough a 22 hour cycle to produce a PEG cake. In yet anotherembodiment, 2 g of gelatin was dissolved in 100 cc pH 2 HCl, in a waterbath at 35° C. 4 g of a two component PEG powder mixture was dissolvedin 2 cc of the gelatin solution, and lyophilized to provide a PEG cake.

In a related embodiment, PEG cakes were prepared by lyophilizing mixedsolutions of PEG-SG, PEG-SH, and collagen at pH 2.0. Animal studies wereperformed on abraded liver capsules in a heparinized porcine model. Twodrops of 0.2M phosphate buffer (pH 9.0) were added to the liver surface,which was bleeding slowly. A piece of cake was placed on the sitewithout any compression. At 5 and 10 minutes, the adhesion of each ofthe PEG cakes to the site were tested. It was observed that the activityof PEG-SG was not reduced during the preparation process, and that thePEG cakes adhered to the abraded liver tissue by covalent bonding. Thecomposition and in vivo performance of the tested samples are summarizedin Table 6.

TABLE 6 Conc. of Conc. of Conc. of Conc. of Mass % collagen In vivoPEG-GS PEG-SH gelatin CIS in PEG after performance Sample (%, w/v) (%,w/v) (%, w/v) (%, w/v) lyophilization (adhesion) 1 20 20 2 0 1.0%Excellent 2 20 20 0 0.29 1.5% Excellent 3 20 20 0 0.52 2.6% Good

Example 18 Pulverized PEG Cake Material

400 mg premixed CoSeal™, 1 g FloSeal™ (e.g. pH 7.1 to 9.5; particlediameter 70 to 400 μm), and 2 to 3 cc of H₂O were combined into a mixedpaste, and lyophilized under a 22 hour cycle to form a cake. As depictedin FIG. 9, the cake 900 was then cracked 910, crushed, and broken powderform 920, and placed in a syringe 930 (e.g. 5 cc or 10 cc syringe). Thetip 940 of the syringe barrel was removed with a blade, the powderedmixture 920 was applied to an injury site 950, and sealant activity wasobserved in situ. Exemplary results are discussed in Examples 10-12. Inanother embodiment, cake were prepared from a three component slurry asdescribed in Table 7.

TABLE 7 Sample Premixed Two-Component PEG FloSeal ™ H₂O PEG % 1 360 mg500 mg 2.3 cc 42% 2 200 mg 500 mg 1.2 cc 48%

Test results on exemplary formulations according to some embodimentsrevealed the following characteristics shown in Table 8.

TABLE 8 FloSeal ™ Weight of (ratio) Weight of Particle Diameter SamplepH FloSeal ™ Mixed PEG FloSeal ™ 1 9.2 5 g 2.5 g 294 μm 2 7.7 5 g 2.5 g308 μm

Example 19 Preparation of Sealant Matrix Composition Fused Pads

PEG pads were prepared with melted CoSeal™ premixtures. Three componentpowders were prepared by mixing FloSeal™ powder of different pH valuesand premixed CoSeal™ (e.g. both PEG components in powder form) accordingto various weight ratios. Lyophilized collagen sponges were used as aback-up support pad to mount the melted three component mixture. In oneembodiment, as depicted in FIG. 10, 0.5 to 1 g of sealant matrixcomposition 1000 was placed on top of a 3×3 cm² section of sponge 1010.The sponge and sealant matrix were baked in an oven at 60 to 70° C. for1 to 2 minutes, and allowed to cool in a desiccator to minimize orprevent contact with the air. The sealant matrix powder was observed toform a coarse film and attach to the sponge to form a fused pad 1020. Inrelated embodiments, several sponges were prepared, each havingdimensions of 3×3×0.3 cm³. Some sponges were coated with a threecomponent mixture of first and second cross-linkable components and ahydrogel-forming component. Some sponges were coated only with a twocomponent mixture of first and second cross-linkable components. Allfused pads were tested in situ on a liver lesion site. Results are shownin Table 9.

TABLE 9 Formulations of three components Fused Wt. of three In vivo cakecomponents performance sponge FloSeal ™ FloSeal ™ CoSeal ™ mounted onBleeding sample pH wt. (g) wt. (g) sponge (g) flow 1 9 0.5 0.2 0.4minimal or no seal 2 8 0.5 0.2 0.4 minimal or no seal 3 8 0.5 0.2 0.4minimal or no seal 4 n/a 0 0.5 0.4 minimal or no seal 5 n/a 0 0.5 0.4minimal or no seal 6 9 1 0.4 0.8 seal

In related embodiments, several powdered compositions were prepared.Some compositions included a three component mixture of first and secondcross-linkable components and a hydrogel-forming component. Somecompositions included only a two component mixture of first and secondcross-linkable components. All compositions were tested in situ on aliver lesion site. Results are shown in Table 10.

TABLE 10 Formulations of three components Wt. of three In vivocomponents performance Sam- FloSeal ™ FloSeal ™ CoSeal ™ applied toBleeding ple pH wt. (g) wt. (g) lesion (g) flow 1 9 0.5 0.2 0.4 to 0.5minimal or no seal 2 8 0.5 0.2 0.4 to 0.5 minimal or no seal 3 9 0.5 0.20.4 to 0.5 minimal or no seal 4 n/a 0   0.5 0.4 to 0.5 minimal or noseal 5 n/a 0.01 lysine 0.5 0.4 to 0.5 minimal or no seal

Example 20 Effect of γ-Radiation on In Vivo Performance

Powdered sealant matrix compositions and sponge-mounted sealant matrixcompositions were prepared and some were γ-radiated to determine theeffects of γ-rays on in vivo performance. No effects were observed, asshown in Table 11.

TABLE 11 Formulations of three components Wt. of three In vivocomponents performance Sponge FloSeal ™ FloSeal ™ CoSeal ™ mounted onBleeding Sample pH wt. (g) wt. (g) sponge (g) flow 1 9 0.5 0.2 0.7 seal2 8 0.5 0.2 0.7 seal 3 (γ) 9 0.5 0.2 0.7 seal 4 (γ) 8 0.5 0.2 0.7 seal 59 0.5 0.2 0.7 seal 6 8 0.5 0.2  0.65 seal 7 8 0.5 0.2 0.6 sealFormulations of three components Wt. of three In vivo componentsperformance Powder FloSeal ™ FloSeal ™ CoSeal ™ applied to BleedingSample pH wt. (g) wt. (g) lesion (g) flow 1 9 0.5 0.2 0.5 seal 2 8 0.50.2 0.5 seal 3 (γ) 9 0.5 0.2 0.5 seal 4 (γ) 8 0.5 0.2 0.5 seal

Example 21 Effect of pH on In Vivo Performance

In vivo studies were performed to evaluate the effect of pH values of ahydrogel-forming component, and the effect of manual applicationmethods, on in situ cross-linking. A Floseal™ of pH 6.75 in a firstsealant composition and a FloSeal™ of pH 9.5 in a second sealantcomposition were compared. In some cases, the sealant matrix compositionwas manually held against the lesion, and in other cases the sealantmatrix composition was applied to or placed on the lesion withoutholding. The composition having Floseal™ of pH 6.75 appeared to provideabout 10 to 30 seconds slower reaction time than the composition havingFloseal™ of pH 9.5. Exemplary study results are shown in Table 12. It isthought that the pH of a hydrogel-forming component may play a role inthe early stages of a cross-linking reaction. The pH of ahydrogel-forming component may effect the speed of gel formation in awet environment (e.g. where bleeding is already occurring). In somecases, if cross-linking does not occur quickly enough, the sealantcomposition may be pushed away from the lesion site.

TABLE 12 Formulations of three components Wt. of three components Invivo performance Powder FloSeal ™ FloSeal ™ CoSeal ™ applied to BleedingApplication Sample pH wt. (g) wt. (g) lesion (g) flow site/method P 70.5 0.2 0.5 no seal liver square (w/o holding) P 9 0.5 0.2 0.5 sealliver square (w/o holding) P 7 0.5 0.2 0.5 seal liver square (w/holding) P 9 0.5 0.2 0.5 seal liver square (w/ holding) P 7 0.5 0.2 0.5seal splenic vein (w/ holding) P 9 0.5 0.2 0.5 seal splenic vein (w/holding)

Example 22 Use of SURGIFOAM™ as Hydrogel-Forming Component

Mixtures of powdered COH102 (pentaerythritoltetrakis-[1-(1′-oxo-5′succinylpentate)-2-poly(oxyethylene)glycol]ether), powdered COH206(pentaerythritol tetrakis-[mercaptoethyl-poly(oxyethylene)glycol]ether),and SURGIFOAM™ Absorbable Gelatin Powder (Ethicon, Somerville, N.J.)were blended at ratios of 1:1:2, 1:1:4, and 1:1:8 by weight and filledinto modified 5 mL syringes. The resulting mixtures were substantiallydry, free-flowing powders. For each composition, two grams were appliedwith gentle compression to a surgically created lesion (approximately 1cm×1 cm×0.3 cm deep) on the liver of a pig. For each of thecompositions, compression was removed after one minute. The COH102 andCOH206 in each composition reacted with each other in the wetenvironment of the lesion, creating a cross-linked hydrogel thatincorporated the SURGIFOAM™ powder and physically sealed the lesionsite. No bleeding was observed from any of the sites treated with thecompositions. After irrigating the treated lesions with saline solution5 minutes after application, no rebleeding was observed. Examination ofthe treated sites two hours later also showed no bleeding.

Example 23 In Vivo Performance of Sealant Matrix Composition withClotting Agent

A sealant matrix composition powder was prepared, containing FloSeal™and CoSeal™ (pre-mixed) in a 4:1 weight ratio. In some embodiments, thisratio provides a degree of cross-linking effective to achieve desiredlevels of chemical polymerization and adherence of the composition totissue. Thrombin powder was added to the sealant matrix compositionpowder at various concentrations. The resulting mixture was tested in ananimal study that involved measuring bleeding scores in liver squaresand comparing hemostatic efficiency of the resulting mixture withsealant matrix compositions that did not contain thrombin.

Testing materials included 0.1 g of pentaerythritoltetrakis[merkaptoethylpoly(oxyethylene)]ether, 0.1 g of Pentaerythritoltetrakis[1-1′-oxo-5′-succinimidylpentanoate)-2-poly(oxoethylene)glycole]ether,0.8 g of crosslinked gelatin particle (FloSeal™), and variousconcentrations (5 k, 2.5 k, 1.25 k, and 0.625 k u/g) of thrombin. In amixing experiment, the four components of the resulting mixture weremixed with a tumble mixer. In a reconstitution experiment, four ml ofthrombin solution (1250 u/ml) was mixed with 0.8 g of FloSeal, and thenfreeze fried for 22 hrs. Then dried mixture was mixed with CoSeal™powder using a tumbler mixer. Without being bound to any particulartheory, it is thought that the reconstituted thrombin formulationcontains thrombin molecules that have penetrated into the matrix ofFloSeal™ so that thrombin may remain in the sealant matrix barrier toenhance hemostatic efficacy. In a pad experiment, a pad was prepared bymounting the resulting four component mixture (sealant matrixcomposition plus thrombin) on top of a Gelfoam sponge, melting themixture, and allowing it to cool and solidify. The oven temperature wasset at about 60° C. to about 65° C. for about one minute.

In an in vivo test, an animal was heparinized to activate clotting timeto reach 3-5 times higher than base line. Formulations were examined onthe bleeding space of liver square (1 cm×1 cm×0.2 cm) that wassurgically produced on a porcine liver. The lesion was irrigatedimmediately after the 5 minute reading to remove excess powder. Treatedlesions areas were scored at 1, 5, 10, and 30 minutes. Materials werepolymerized upon the contact with blood then tightly adhered to thelesion. The sealant matrix barrier mechanically sealed the bleedingareas to act as a mechanical sealant by bonding to the tissues. In an invitro test, thrombin was heated at about 60° C. for 5 minutes and foundto be fully active. In a prepared Gelfoam pad, it was found thatthrombin activity was lost.

Results of an acute in-vivo evaluation are provided in Table 13.Bleeding from the lesions were scored from “0” as no bleeding to “4” assevere bleeding. Based on the observed bleeding scores here, all samplestested showed no bleeding. No significant advantage was observed fromthe addition of thrombin to the sealant matrix composition. The use ofthrombin did not show any benefits in primary hemostasis, although itmay augment secondary hemostasis/clot formation and wound healing.

TABLE 13 Lot Sealant Matrix Thrombin (unit/g) No. Composition Mixed orReconstituted 1′ 5′ 10′ 20′ 1 no thrombin 0 0 0 0 2 with thrombin 625,mixed 0 0 0 0 3 with thrombin 2500, mixed 0 0 0 0 4 with thrombin 5000,mixed 0 0 0 0 5 with thrombin 1250, mixed 0 0 0 0 1 no thrombin 0 0 0 00 5 with thrombin 1250, mixed abort 5 with thrombin 1250, mixed 0 0 0 04 with thrombin 5000, mixed 0 0 0 0 4 with thrombin 5000, mixed 0 0 0 01 no thrombin 0 0 0 0 0 6 with thrombin 625, reconstituted 0 0 0 0 7with thrombin 2500, reconstituted abort 7 with thrombin 2500,reconstituted 0 0 0 0 7 with thrombin 2500, reconstituted 0 0 0 0 8 nothrombin 0 0 0 0 0 (sponge) 9 with thrombin 2500, mixed 0 0 0 0 (sponge)

Example 24 Effect of PEG Concentration on Gel Strength

The effect of PEG concentration on gel strength is shown in Table 14 andFIG. 11, according to one embodiment of the present invention. Tensiletests were run following the gel formation. Gels were prepared byallowing reaction of three components powder (e.g. sealant matrixcomposition that includes first and second cross-linkable components anda hydrogel-forming component) in plastic molds (3×1×0.3 cm). Porcineplasma (1 ml, Baxter animal number S-264) was added to a sealant matrixcomposition powder (0.60-0.65 g) to initiate gel formation then allowedto cure at room temperature for approximately 30 minutes. Both ends ofthe gel were taped with scotch tape using cyanoacrylate glue to createthe gripping spaces for pulling apart (1×1 cm). From the tensiletesting, Peak force (N) and deflection at maximum load (cm) weremeasured to extend the gel until the break. 1×0.3 cm is the effectivesurface area. The original effective length of gel is 1.0 cm. Applying anormal stress to the rectangular shape of gel until it breaks byChatillon TCD200 tester was the determination factor of the tensilestrength. Results of the test showed that a higher concentration ofpolymer can increase the strength of the sealant matrix composition gel.

TABLE 14 Effective Curing Sample Material Area, Speed time Force F/0.3cm2 Number Tested cm square mm/min min N F/0.1 cm2 334-25-1 10% PEG 1 ×0.3 12.7 60 2.69 8.97 334-25-2 10% PEG 1 × 0.3 12.7 60 2.12 7.07334-25-3 10% PEG 1 × 0.3 12.7 60 2.11 7.03 Ave. 2.31 7.69 Stdev. 0.331.11 334-25-4 20% PEG 1 × 0.3 12.7 55 3.80 12.67 334-25-5 20% PEG 1 ×0.3 12.7 60 3.93 13.10 334-25-6 20% PEG 1 × 0.3 12.7 55 3.47 11.57334-25-7 20% PEG 1 × 0.3 12.7 60 2.33 7.76 Ave. 3.38 11.28 Stdev. 0.732.43 316-80-1 30%, PEG 1 × 0.3 12.7 70 4.04 13.46 316-80-2 30%, PEG 1 ×0.3 12.7 60 4.55 15.17 316-80-3 30%, PEG 1 × 0.3 12.7 60 5.12 17.06316-80-4 30%, PEG 1 × 0.3 12.7 60 4.68 15.60 316-80-5 30%, PEG 1 × 0.312.7 55 4.49 14.97 316-80-6 30%, PEG 1 × 0.3 12.7 60 4.52 15.07 Ave.4.57 15.68 Stdev. 0.35 0.97

Example 25 Effect of PEG Concentration on Swelling Ratio

The effect of PEG concentration on swelling ratio is shown in FIGS. 12,13, and 14, according to one embodiment of the present invention.Swelling studies were carried out for the characterization of sealantmatrix composition gels. When in contact with an aqueous environment,the hydrophilic polymer swells to form a hydrogel. Once a gel is formed,water molecules diffuse freely through a rather loose network formed byswollen FloSeal™ particles. Upon further addition of water,COH102-COH206 contacts are broken and individual polymer molecules aredissolved in water. Sealant matrix composition gels were prepared bymixing CoSeal™ and FloSeal™ at four different concentrations (5%, 10%,20%, and 30% w/w) of polymer and by reactions with the same amount ofporcine plasma (1.7 ml/g powders). The gel was cured for 30 minutes andthen allowed to swell in saline at room temperature. Periodically,buffer was drained and the weight of the remaining gel was determined.The change in the weight of gel was monitored. The swelling ratio, Q,was calculated from the following equation:

Q=W*/W

where W* is the wet weight and W is the original weight. The swellingratio increased with increasing of polymer concentration. Without beingbound by any particular theory, the apparent decline in swell ratio maybe interpreted as a loss of gel material, as the gel slowly eroded. Theend of the experiment is scored as the time when the gel disintegratesinto several small pieces or becomes so slimy and weak that it isimpossible to decant the free buffer from the gel. Water continues topenetrate toward the core and finally gel is converted to a viscoussolution of PEG and gelatin particles. It took about 2-3 weeks for allmaterials to fall apart (FIG. 14). It appears that percent CoSeal™ in asealant matrix composition powder can have a profound impact on thestability of a sealant matrix composition gel. The dissolution rate ofthe sealant matrix composition gel varies depending on the crosslinkingdegree of polymers. Results showed that the higher concentration ofCoSeal™ can cause a stronger gel stability and can also cause moreswell. The relative persistence of such gel in vitro may be expected tobe similar to that in vivo.

The above examples provide ample illustration that compositionsaccording to the present invention can be effective sealants. Thecompositions can polymerize in situ with physiological liquid or blood,and can seal or adhere to tissue very tightly.

Although the foregoing invention has been described in some detail byway of illustration and example, for purposes of clarity ofunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims. All patents,publications, articles, books, and other references materials discussedherein are incorporated by reference for all purposes.

Example 26 Assessment of Hemostatic Properties in Animal Models ofCertain Formulations

Formulation No. 334-77

One gram of PEG-A powder (Pentaerythritoltetrakis[merkaptoethylpoly-oxyethylene]ether, MW 10,000), 1 g of PEG-Bpowder (Pentaerythritoltetrakis[1-1′-oxo-5′-succinimidylpentanoate-2-poly-oxoethyleneglycole]ether,MW 10,000), and 8 g of FloSeal™ were placed in a mixing bottle (50 mlsize) and loaded into the Inversina Tumbler Mixer for mixing. Mixture ofthree components were blended for 10 minutes until fully mixed. Sixsyringes (5 ml size) were filled with about 1.5 g of the mixture.

Formulation No. 334-77-1

A 1.5 g sample of Formulation No. 334-77 was mounted on a piece ofGelfoam (3×4 cm², Compressed Gelfoam, Upjohn manufactured, NDC0009-0353-01). Gelfoam topped with the sample was baked in a vacuum ovenat 60-65° C. for 1 min until the sample began to melt. The material wasthen allowed to cool and solidify. Two pieces of the resulting cake onGelfoam were placed in a pouch inserted with desiccant and sealed.

Formulation No. 334-77-4

A sample of Formulation No. 334-77 was placed on a piece of collagensponge and baked. Sponges were prepared by lightly crosslinking collagenfibers by glutaraldehyde solution (5 k ppm) and by freeze-dryingcollagen solution (1.0%) using VirTis Genesis Freeze Dryers. A collagenpad (3×4 cm²) was carefully layered with a 1.5 g sample of FormulationNo. 334-77, then heated in a vacuum oven at 60-65° C. for 1 min untilthe sample began to melt. The material was then allowed to cool andsolidify. Each resulting collagen pad was placed in a pouch insertedwith desiccant and sealed.

Methods:

Surgical Procedures:

Animals (NZW rabbits, female, weight approximately 3 kg) wereanesthetized and received intravenous heparinization at a dose of 4.000IU/kg 30 minutes prior to partial liver resection.

Liver Resection Model:

A median laparotomy was performed and the left lobe of the liver exposedand clamped. Part of the left lateral liver lobe was resected. Oozingwas controlled by application of the test item. Application and settingtime was standardized not to exceed 300 seconds. The hemostatic clampwas removed five minutes later when primary hemostasis was expected tobe achieved.

Liver Abrasion Model:

A median laparotomy was performed and the left lobe of the liverexposed. A superficial circular lesion with a diameter of 2 cm and adepth of 2 mm was abraded on the surface of the liver lobe. This wasaccomplished using a drilling machine with a grinding disc attachment(bore grinder PROXXON FBS 230/E; grit size P40, rotational speed5.000/min). The resultant small vessel or capillary bleeding or oozingthus generated was treated with one of the formulations.

After allowing an observation period of 15 minutes, the left liver lobewas returned to its original position in the abdominal cavity. Ifhemostasis is achieved, the abdomen will be closed and the Omentumresected (Synthofil® 2/0). The muscle and skin incision will be suturedseparately using Synthofil® 2/0 as interrupted sutures in a two-levelmanner.

After 24 hours, the animals were sacrificed in anesthesia by an overdoseof Pentobarbital Natrium (approx. 320 mg i.v./animal). Aftereuthanization an autopsy was performed. The abdomen was visuallyinspected for the presence of blood and/or blood clots resulting fromrebleeding. If present, blood and/or blood clots were swabbed usingpre-weighed surgical swabs, and the weight determined. If no hemostasiswas achieved, animals were sacrificed by an overdose of PentobarbitalNatrium (approx. 320 mg i.v./animal) and only primary endpoints will beevaluated.

Results:

The present study was aimed to assess the hemostatic properties offormulations #334-77, #334-77-1 and #334-77-4). Two very harshhemostasis models were used: (1) the liver resection and (2) the liversurface model in highly heparinized rabbits.

After applying formulation #334-77 powder onto the bleeding wound it wasfound helpful to press the formulation onto the wound surface to obtainhemostasis. It was difficult to achieve this pressure with a drysurgical latex glove, since the powder had more adherence to the glovethan to the wound. However, application of pressure with a wet glove waseasier. The formulation formed a tight membrane after it came intocontact with the moisture of blood. After application it lead tohemostasis in many cases, even in the harsh models used in this example.If hemostasis was not completely achieved after the first application,and there was an oozing bleeding underneath the layer formed, it wasdifficult to adequately stop the bleeding simply by the application ofmore formulation #334-77. It may be difficult to restrict application ofthe formulation only to the place where it is needed to stop thebleeding as the powdered formulation can fall into the abdominal cavityand adhere to the abdominal cavity if sufficient care is not taken.Therefore, proper application of formulation #334-77 is helpful.

In contrast, formulation #344-77-4 could easily be applied in a layer ofconstant thickness over a large area of tissue and with sufficientpressure in order to obtain hemostasis. Formulation #344-77-4, with thenative collagen pad backing, remained adherent to the liver lobe afterapplication and acted as a hemostat and glue, gluing the pad onto thewound and the liver capsule. Such a biodegradable backing can add moreefficacy to the powder component in achieving hemostasis. Thebiodegradable backing can also confer flexibility to the formulation,allowing the formulation to be bent over edges of a resection duringapplication. Two animals were treated with this formulation, one in thesurface model and one in the resection model. Acute hemostasis wasobtained in both models. Only the animal treated in the surface modelsurvived with no postsurgical bleedings for 24 h. The collagen fleecewas still at the site of application after 24 h. The animal treated inthe resection model bled overnight to death and the fleece was detached.A difference between the two experiments was that in the first thefleece was pressed in the dry state onto the wound and in the secondpressure with a wet gauze swab was used. The findings are shown in Table15.

TABLE 15 Animal Experiment 1 1a Liver resection model: (#334-77-1) Leftliver lobe. Application without clamping. During application the Gelfoampad was brittle and stiff and could not be bent in dry state around theedges of the resection. Was pressed 2 min with a wetted gauze swab (0.9%NaCl) on the resection surface and the intact liver capsule around theresection. The powder adhered firmly to the wound surface but not to theGelfoam backing. Non-adhering powder was rinsed with 0.9% NaCl. Bleedingwas stopped with exception of one point on the edge of the resectionwere oozing bleeding was observed. 1b Surface model: (#334-77-1) Leftmedian liver lobe. Application without clamping. Formulation #334-77-1was pressed 2 min with a wetted gauze swab (0.9% NaCl) on the woundsurface. The Gelfoam backing was removed. The formulation was adheringto the wound. Bleeding was stopped. 2 2a Liver resection model:(#334-77) Left lateral liver lobe. Formulation #334-77 was applied tothe bleeding surface and pressed with the dry latex glove. The powderadhered more strongly to the glove as to the wound surface. Theformulation layer was removed with the glove. 2b Liver resection model:(#334-77) Same left lateral liver lobe as in 2a. #334-77 was appliedwith the wet glove and pressed 10 s to the wound surface. No adherenceof powder to the glove. A layer was formed over the wound surface.Oozing bleeding beneath the powder was observed. 2c Liver resectionmodel (#334-77) Left median liver lobe, application with clamping.Formulation #334-77 was applied on the bloody surface and pressed on thesurface with a metal foil. The clamp was released after 5 min. Slightoozing bleeding at the edge of the resection. It was tried to stop thisbleeding by applying more formulation. Bleeding could not be stoppedcompletely. The powder layer was removed. The layer formed a tightmembrane but with only little adherence to the wound surface. 2d Liverresection model: (#WR334-77) Same liver lobe as in 2c, but a new cut wasdone in order to promote bleeding. Application after clamping the liverlobe. Formulation was pressed 2 min with the scalpel on the wound.Bleeding could not be stopped 3 3a Surface model: #WR334-77+ equinecollagen pad. #344-77 powder was spread on a thin layer of an equinecollagen pad. Holes were punctured in the collagen pad with an injectionneedle from the side with the formulation layer. Some formulationpressed into the holes. The formulation layer was thinner than as in theformulation variants. The fleece was applied dry, without clamping theliver lobe. The fleece was pressed with the glove for 2 min. No bleedingwas observed. The pad was removed. Good adherence to the liver capsuleand less adherence to the wound surface was observed. 3b Surface model:Formulation-Collagen-Pad (#334-77-4) Same wound as in 3a. The pad wasapplied in dry state and pressed for 2 min on the wound surface. The padwas more flexible (bendable) compared to the fleece with the Gelfoambacking. This was favorable for the ease of application. The formulationdid not detach from the collagen pad. The whole formulation-collagen padwas adhering to the wound and liver capsule. No bleeding was observed).The collagen pad was wetted with 0.9% NaCl and the rabbit closed. Theanimal survived 24 h than it was sacrificed. In the post mortemexamination the fleece was on place and no bleeding occurred during 24h.

1. A sealant composition for use in treating an individual, comprising:a porous layer, a first component associated with the porous layer, thefirst component comprising a nucleophilic polymer, and a secondcomponent associated with the porous layer, the second componentcomprising an electrophilic polymer.
 2. The sealant compositionaccording to claim 1, wherein each of the first and second components ispresent as a gel.
 3. The sealant composition according to claim 1,wherein the porous layer comprises a member selected from the groupconsisting of a pad, a sheet, a film, and a sponge.
 4. The sealantcomposition according to claim 1, wherein the porous layer comprises amember selected from the group consisting of collagen, fibrin,cellulose, and chitosan.
 5. The sealant composition according to claim1, wherein the first component nucleophilic polymer comprises a memberselected from the group consisting of a dilysine, a trilysine, aquatralysine, a pentalysine, a dicysteine, a tricysteine, aquatracysteine, a pentacystein, and an oligopeptide or polypeptidecomprising two or more lysines or cysteines.
 6. The sealant compositionaccording to claim 1, wherein the second component electrophilic polymercomprises two or more succinimidyl groups.
 7. The sealant compositionaccording to claim 1, wherein the second component comprises apolyethylene glycol containing a succinimidyl group.
 8. A method oftreating a tissue of an individual, the method comprising: applying asealant composition to the tissue of the patient, the sealantcomposition comprising a first component having a nucleophilic polymerand a second component having an electrophilic polymer, and wherein thefirst component and the second component are fixed on a supportcomprising a member selected from the group consisting of a protein, acarbohydrate, and a synthetic polymer.
 9. The method according to claim8, wherein each of the first and second components is present as a gel.10. The method according to claim 8, wherein the sealant compositionfurther comprises a hydrogel-forming component fixed on the support. 11.The method according to claim 10, wherein the hydrogel forming componentcomprises a biologic polymer selected from the group consisting ofgelatin, collagen, albumin, hemoglobin, fibrogen, fibrin, casein,fibronectin, elastin, keratin, laminin, and derivatives and combinationsthereof.
 12. The method according to claim 8, wherein the support isporous and comprises a member selected from the group consisting of apad, a sheet, a film, and a sponge.
 13. The method according to claim 8,wherein the support comprises a member selected from the groupconsisting of collagen, fibrin, cellulose, and chitosan.
 14. The methodaccording to claim 8, wherein the first component nucleophilic polymercomprises a member selected from the group consisting of a dilysine, atrilysine, a quatralysine, a pentalysine, a dicysteine, a tricysteine, aquatracysteine, a pentacystein, and an oligopeptide or polypeptidecomprising two or more lysines or cysteines.
 15. The method according toclaim 8, wherein the second component electrophilic polymer comprisestwo or more succinimidyl groups.
 16. The method according to claim 8,wherein the second component comprises a polyethylene glycol containinga succinimidyl group.
 17. The method according to claim 8, wherein thesealant composition further comprises an active agent.
 18. The methodaccording to claim 8, wherein the sealant composition further comprisesa hemostatic agent selected from the group consisting of thrombin,fibrinogen, and a clotting agent.
 19. A method of making a sealantcomposition for use in treating a tissue of an individual, the methodcomprising: obtaining a porous layer; and applying a mixture to theporous layer, the mixture comprising a first component having anucleophilic polymer and a second component having an electrophilicpolymer.
 20. The method according to claim 19, wherein each of the firstand second components is present as a gel.
 21. The method according toclaim 19, wherein the porous layer comprises collagen.
 22. The methodaccording to claim 19, wherein the first component nucleophilic polymercomprises a member selected from the group consisting of a dilysine, atrilysine, a quatralysine, a pentalysine, a dicysteine, a tricysteine, aquatracysteine, a pentacystein, and an oligopeptide or polypeptidecomprising two or more lysines or cysteines, and wherein the secondcomponent comprises a polyethylene glycol containing a succinimidylgroup.